3157 


HAWAII  AGRICULTURAL  EXPERIMENT  STATION 
HONOLULU,  HAWAII 

Under  the  supervision  of  the 
UNITED  STATES  DEPARTMENT  OF  AGRICULTURE 


BULLETIN  No.  57 


EDIBLE  CANNA 

IN  THE  WAIMEA  DISTRICT 

OF  HAWAII 


BY 
J.  C.  RIPPERTON,  Chemist 

and 

R.  A.  GOFF,  Extension  Agent  for  the  Island  of  Hawaii 

▼  ■& 

lamed  April,  1928 


UNITED  STATES 
~"  GOVERNMENT  PRINTING  OFFICE 
WASHINGTON 
1928 


HAWAII  AGRICULTURAL  EXPERIMENT  STATION,  HONOLULU 

[Under  the  supervision  of  the  Office  of  Experiment  Stations,  United  States  Department  of  Agriculturel 

E.  W.  Allen,  Chief,  Office  of  Experiment  Stations 
Walter  H.   Evans,   Chief,   Division  of  Insular  Stations,  Office  of  Experiment 

Stations 


STATION  STAFF 

J.  M.  Westgate,  Director. 
W.  T.  Pope,  Horticulturist. 
H.  L.  Chung,  Agronomist. 
J.  C.  Ripperton,  Chemist. 
R.  A.  Goff,  Extension  Agent  for  the  Island  of  Hawaii,  HUo,  Hawaii,  Territory  of 

Hawaii. 
Mabel  Greene,  Boys'  and  Girls1  Club  Leader. 
H.  F.  Willey,  Superintendent,  Haleakala  Demonstration  Farm,  Makawao,  Maui, 

Territory  of  Hawaii. 
R.  K.  Lum,  Junior  Tropical  Agronomist. 
John  Castro,  Plant  Propagator.1 

1  Appointed  December  3,  1925. 


HAWAII  AGRICULTURAL  EXPERIMENT  STATION 
HONOLULU,  HAWAII 

Under  the  supervision  of  the 
UNITED  STATES  DEPARTMENT  OF  AGRICULTURE 


BULLETIN  NO.  57 


Washington,  D.  C. 


April,  1928 


EDIBLE  CANNA  IN  THE  WAIMEA  DISTRICT  OF 

HAWAII 

By  J.  C.  Ripperton,  Chemist,  and  R.  A.  Goff,  Extension  Agent  for  the  Island  of 

Hawaii 


CONTENTS 


Introduction 1 

The  Waimea  district 2 

Climate 2 

Soils 5 

Agricultural  retrospect 6 

Adaptation  of  edible  canna 7 

Field  practices 7 

Windbreaks 9 

Experiments  with  edible  canna.- 11 

Methods  of  investigation . 11 

Application  of  methods 12 

Results  of  genealogization - 13 


Page 
Experiments  with  edible  canna  (Continued). 

Selection  of  rootstocks  for  "seed" 14 

Treatment  of  "seed" 19 

Depth  of  planting 22 

Number  of  "seed"  per  hill 23 

Spacing  and  mulching  with  canna  tops..  24 

Fertilizers 24 

Time  of  harvesting 25 

Feed  and  fertilizer  value 35 

Manufacture  of  starch 38 

Summary 40 

Literature  cited 41 


INTRODUCTION 

The  farmers  of  Hawaii  have  at  different  times  attempted  to  pro- 
duce starch  from  the  root  crops  of  cassava,  sweet  potatoes,  and  taro. 
None  of  these  attempts,  however,  proceeded  any  further  than  to 
meet  the  needs  of  a  small  local  demand.  Tree-fern  starch  was  manu- 
factured on  a  small  scale  on  the  island  of  Hawaii  in  1920,  but  the  in- 
dustry was  abandoned  two  years  later  because  of  the  high  cost  of 
securing  the  raw  material  from  the  forests  and  the  very  slow  rate  of 
growth  of  the  trees,  which  makes  it  impracticable  to  replant  cut- 
over  areas  (8,  pp.  7-9)} 

The  remarkable  growth  of  small  plantings  of  edible  canna  {Canna 
edulis)  at  Waimea,  Hawaii,  led  to  a  fertilizer  experiment  with  the 
crop  in  the  Homestead  tract  in  that  region  in  1923.  Since  then 
experiments  totaling  15  acres  have  been  carried  on  in  cooperation 
with  a  private  starch-manufacturing  concern.  The  homesteaders 
of  the  district  have  shown  considerable  interestTin  the  development 
of  the  edible  canna,  devoting  approximately  125  acres  to  their  first 
crop.2    A  starch  mill  was  erected  at  Waimea  in  October,  1925,  manu- 


»  Reference  is  made  by  numbers  (italic)  to  "Literature  cited."  p.  41. 

i  The  writers  wish  to  thank  the  Waimea  Starch  Co.  for  its  generous  cooperation  and  help  in  making  pos- 
sible the  experiments  reported  upon. 

83065—28 1 


Z  BULLETIN    57,    HAWAII   EXPERIMENT   STATION 

facture  of  the  commercial  product  was  begun  in  March,  1926,  and  the 
starch  appeared  on  the  local  markets  shortly  afterwards. 

The  data  presented  in  this  bulletin  represent  largely  the  results  of 
field  experiments  with  edible  canna  at  Waimea. 

THE  WAIMEA  DISTRICT 

The  Waimea  district  (fig.  1),  comprising  an  area  of  approximately 
15  miles  square,  is  a  slightly  rolling  table-land  lying  2,600  to  2,700 
feet  above  sea  level.  The  plateau  is  volcanic  in  origin,  the  surface 
being  a  mixture  of  disintegrated  lava,  pumice,  and  ash.  The  ash 
extends  to  a  depth  of  2  to  3  feet  in  some  places,  and  small  outcroppings 
of  partially  intact  lava  flows  occur  in  others.  That  part  of  the  dis- 
trict in  which  the  Homestead  tract  is  located  is  the  only  part  devoted 


Fig.  1.— General  view  of  the  Waimea  district.  Foreground,  a  section  of  the  homesteads;  background, 

Mauna  Kea 

to  agriculture  at  present,  lies  close  to  the  foothills  of  the  Kohala 
Range,  and  is  overlain  to.  some  extent  by  the  wash  from  the  mountains. 
The  growth  of  the  dense  forest  which  covered  the  plains  40  or  50 
years  ago  is  said  to  have  been  destroyed  by  fires  and  cattle,  and  the 
light,  fluffy  surface  soil  to  have  been  carried  by  the  constantly  recur- 
ring strong  winds  from  the  plains  to  the  lee  of  the  Kohala  Mountains 
in  the  Kawaihae  district.  This  fact  probably  accounts  for  the  poor 
growth  made  in  the  central  part  of  the  plains  by  range  grasses  which 
grow  luxuriantly  at  the  base  of  the  mountains. 


CLIMATE 


The  climate  of  the  Waimea  district  is  influenced  by  its  location 
between  two  comparatively  high  mountains.  The  height  of  Mauna 
Kea^  (13,825  feet)  deflects  the  normal  northeast  trade  winds  along 
the  lower  Hamakua  district  toward  the  Waimea  pass,  where,   at 


EDIBLE    CANNA   IN   WAIMEA   DISTRICT   OF   HAWAII  6 

Ookala,  the  wind  is  from  the  southeast.  As  a  result,  the  wind  in- 
creases considerably  in  velocity  through  Waimea. 

Occasionally  the  prevailing  trade  winds  are  supplanted  by  Kona 
(south)  winds.  These  usually  give  rise  to  unsettled  weather  with 
strong  winds  and  are  regarded  as  deleterious  both  to  health  and  to 
crop  growth. 

Table  lfcompares  the  climatological  data  of  Waimea  and  other 
districts. 


Table  1. — Comparison  of  climatological  data  of  Waimea  and  other  districts  ! 


Locality 


Length 

of 
record 


Waimea 

Ookala 

Honokaa 

Ahualoa  homesteads . 
Puuhinei  Paddock.. 


Years 
11 
13 
11 

7 


Alti- 
tude 

Temperature 

Num- 
ber of 
cloudy 
days  s 

Maxi- 
mum 

Mini- 
mum 

Mean 
maxi- 
mum 

Mean 
mini- 
mum 

Annual 
mean 

Feet 
2,700 
400 
1,042 
2,551 
1,500 

op 

83 
88 
91 

°F 
34 
53 
53 

op 
69.8 
79.0 
79.3 

0  F 
55.4 
64.7 
63.7 

°F 
62.9 
71.9 
71.5 

231 
220 
184 

Annual 
precipi- 
tation 


Inches 
43.50 

118.  00 
72.98 

117. 53 
19.00 


1  Taken  from  the  monthly  publication  Climatological  Data,  Hawaiian  Section,  U.  S.  Dept.  Agr.  Weather 
Bur.  (IS). 
*  0.01  inch  of  rain  or  more. 

The  rainfall  is  copious  on  the  rising  slope  of  practically  all  the 
Hamakua  district,  but  decreases  rapidly  toward  the  west  on  the 
comparatively  level  plains  of  Waimea.  In  progressing  from  Ookala 
(400  feet)  to  Ahualoa  homesteads  (2,551  feet)  the  rainfall  remains 
practically  constant,  118  inches  of  rain  falling  at  the  former  place, 
and  117  inches  at  the  latter  place.  From  Ahualoa  homesteads  to 
Waimea,  a  distance  of  approximately  10  miles,  the  elevation  increases 
only  1 59  feet,  whereas  the  annual  rainfall  decreases  to  43  inches.  At 
Puuhinei  Paddock  (1,500  feet),  about  10  miles  west  of  Waimea, 
the  rainfall  is  only  19  inches. 

Notwithstanding  the  lower  annual  rainfall,  the  Waimea  district 
gives  the  appearance  of  being  as  well  watered  as  are  the  lower  levels 
where  the  precipitation  is  several  times  as  heavy.  As  is  shown  by 
the  table,  Waimea  exceeds  the  lower  levels  in  number  of  cloudy  days; 
that  is,  days  during  which  0.01  inch  or  more  of  rain  falls.  With  the 
temperature  so  frequently  at  the  dew  point,  heavy  dews  and  almost 
daily  fogs  occur,  and  the  rate  of  evaporation  is  of  course  compara- 
tively small.  These  factors,  together  with  the  loose  soil  and  com- 
paratively level  topography  which  prevents  losses  by  run-offs,  make 
possible  the  maximum  utilization  of  the  rainfall  by  the  crops. 

The  table  shows  that  Waimea  has  a  mean  temperature  of  about 
9°  F.  less  than  the  lower  windward  levels.  The  range  from  the  mean 
maximum  to  the  mean  minimum  is  the  same,  being  14.3°  F.  at  Ookala 
and  14.4°  F.  at  Waimea.  The  extreme  range  over  a  period  of  13 
years  at  Ookala  was  35°  F.  and  at  Waimea  49°  F.  The  lowest 
recorded  temperature  at  Waimea  was  34°  F. 

In  Table  2  are  given  the  monthly  and  annual  precipitation  for  the 
years  1919-1926,  and  a  summary  of  the  average  monthly  precipi- 
tation for  the  years  1891-1918. 


BULLETIN    57,   HAWAII   EXPERIMENT  STATION 


Table  2. — Monthly  and  annual  precipitation  at  Waimea  for  the  calendar  years 
1 919-1926 1 x  and  summary  of  the  average  monthly  rainfall  for  the  period  1891- 
1918 23 


Month 

1919 

1920 

1921 

1922 

1923 

1924 

1925 

1926 

Average, 
1891-1918 

Inches 
3.25 
1.59 
2.86 
2.79 
1.89 
2.85 
3.18 
3.06 
2.04 
.24 
.64 
4.78 

Inches 
7.06 
1.55 
3.15 
2.98 
1.22 
1.20 
2.26 
2.71 
2.27 
1.34 
3.79 
6.51 

Inches 
6.63 

.65 
3.51 
3.73 
1.78 

.93 
4.07 
2.44 
2.60 
1.68 
12.98 
5.14 

Inches 
6.61 
8.91 
9.06 
3.05 
1.47 
2.37 
2.27 
4.75 
5.09 
2.67 
2.86 
.93 

Inches 
12.60 
2.79 
8.43 
8.96 
2.26 
2.87 
3.70 
3.49 
2.32 
3.29 
2.49 
9.06 

Inches 
1.85 
3.60 
2.34 
4.46 
1.60 

.58 
2.82 
1.55 

.98 
6.14 
8.95 
3.40 

Inches 
2.86 
1.35 
7.39 
6.44 
2.80 
3.94 
2.11 
4.00 
2.23 
3.04 
2.07 
2.20 

Inches 
1.84 
2.31 
1.18 
3.06 
3.62 
1.77 
4.07 

Inches 
4.76 

February 

4.64 

March 

4.98 

April 

3.66 

May 

3.14 

June 

2.45 

July 

2.89 

August ... 

3.25 

September 

2.19 

October 

2.61 

November 

3.52 

December 

5.4] 

Total 

29.17 

36.04 

46.14 

50.04 

62.26 

38.27 

40.43 

43.50 

Departure  from  nor- 
mal  

-14.33 

-7.46 

+2.64 

+6.54 

+18. 75 

-5.23 

-3.07 

Number     of     rainy 
days  * .. 

246 

223 

266 

282 

293 

274 

265 

231 

1  a/). 

1  The  data  in  Tables  1  and  2  were  obtained  from  the  United  States  Weather  Bureau  Station,  located  at 
lot  No.  52  of  the  first  series  of  homesteads.  This  is  2lA  miles  west  of  the  experimental  plat  and  would  be 
somewhat  drier  than  at  the  plats,  since  the  rainfall  decreases  toward  the  west. 

*  (12).  *  0.01  inch  of  rain  or  more. 

While  the  rainfall  in  a  single  year  is  often  subject  to  wide  variation 
from  month  to  month,  the  average  from  1891  to  1918  shows  a  fairly 
uniform  distribution  throughout  the  year.  The  heaviest  rainfall  for 
the  period  1891-1918  occurred  during  December,  January,  February, 
and  March.  In  these  four  months  occurs  nearly  half  the  rainfall  of 
the  year.  During  the  remaining  eight  months  the  maximum  vari- 
ation is  2.19  to  3.66  inches  per  month.  The  June  and  October  mini- 
ma, which  are  characteristic  of  Hawaiian  climate  (#),  are  apparent 
but  somewhat  less  pronounced  than  in  most  other  localities.  The 
monthly  rainfall  for  the  period  1919-1926  shows  large  deviations 
from  the  normal,  but  no  greater  comparatively  than  occur  at  the 
lower  levels.  Moreover,  subnormal  annual  rainfall  often  is  the  result 
of  small  precipitation  during  the  winter  months  and  little  depression 
during  the  drier  summer  months. 

In  Table  3  is  given  the  average  monthly  temperature  at  Waimea 
for  the  calendar  years  1919-1926,  and  a  summary  of  the  average 
monthly  temperature  for  the  period  1908-1918. 

Table  3. — Average  monthly  temperature  at  Waimea  for  the  calendar  years  1919- 
1926 l  and  a  summary  of  the  average  monthly  temperature  for  the  period  1908- 
1918* 


Month 

1919 

1920 

1921 

1922 

1923 

1924 

1925 

1926 

Average, 
1908-1918 

January 

op 

58.6 
60.6 
60.8 
62.4 
62.8 
65.6 
63.8 
64.8 
66.0 
65.6 
65.1 
64.2 

°F. 

62.1 
60.4 
60.7 
61.4 
66.4 
65.0 
65.2 
64.9 
64.3 
64.0 
62.2 
61.1 

°F. 

sa  5 

63.2 
62.1 
60.8 
65.4 
63.8 
63.4 
64.0 
62.8 
65.0 
63.0 
60.9 

°F. 

59.9 
57.7 
59.8 
61.4 
61.8 
64.0 
64.0 
64.2 
64.4 
65.4 
62.7 
62.6 

°F. 
60.1 
62.7 
61.4 
62.5 
63.0 
63.3 
64.1 
66.4 
66.5 
66.2 
63.3 
61.2 

°F. 
61.3 
62.0 
60.8 
64.4 
64.4 
64.9 
64.6 
64.4 
65.3 
64.6 
64.8 
63.2 

°F. 
61.4 
62.8 
61.2 
58.8 
61.0 
62.2 
65.2 
64.5 
65.8 
64.7 
65.0 

oF 

63.5 
63.6 
63.1 
62.0 
64.0 
68.7 
66.8 

°F. 
61.1 

February 

60.6 

March. 

61.2 

April 

61.8 

May 

63.1 

June 

63.2 

July 

64.0 

August 

64.9 

September 

65.3 

October. 

64.9 

November 

63.3 

December 

61.2 

Average 

63.4 
+0.5 

63.1 
+0.2 

62.8 
-0.1 

62.3 
-0.6 

63.4 
+0.5 

63.7 
+0.8 

62.9 

Departure  from  nor- 
mal  

I""~ 

a/). 


OB). 


EDIBLE   CANNA   IN   WAIMEA   DISTRICT   OF  HAWAII  5 

Table  3  shows  that  the  Waimea  district  has  the  same  uniformity 
of  t  temperature  throughout  the  year  that  is  characteristic  of  the 
Hawaiian  Islands  as  a  whole.  The  10-year  average  for  February, 
the  coldest  month,  was  but  4.7°  F.  less  than  that  for  September,  the 
warmest  month.  The  greatest  annual  departure  from  the  normal 
was  0.8°  F. 

SOILS 

The  soils  of  the  Waimea  district,  being  of  a  porous  nature,  offer  strik- 
ing contrast  to  the  exceedingly  heavy  soils  of  the  majority  of  the 
lower  lying  sugar-cane  and  pineapple  lands  of  the  islands  (5, p.  83-35). 
Mechanical  analyses  of  the  heavy  types  show  a  clay  content  ranging 
usually  from  10  to  as  high  as  58  per  cent  and  correspondingly  high 
amounts  of  fine  silt  and  silt  fractions,  but  negligible  amounts  of  coarse 
sand  or  fine  gravel.  The  heavy  soils  pack  with  rocklike  hardness, 
can  be  plowed  only  with  difficulty,  and  puddle  if  plowed  or  cultivated 
when  they  are  too  wet.  In  the  Waimea  district  the  soils  are  light, 
fluffy,  and  deep  and  can  be  easily  plowed  with  an  ordinary  mold- 
board  plow  and  light  team.  Such  soils  show  little  tendency  to  pack 
and  do  not  puddle  when  worked  during  wet  weather. 

Table  4  gives  the  analyses  of  soils  of  the  Waimea  district. 

Table  4. — Analyses  of  soils  of  the  Waimea-Puukayu,  Waikii,  and  Makahalau 

sections 


Constituent 


Waimea- 

Puukapu  Waikii     ;  Makahalau 

section;  section;1       section;1 

soil  No.  474  soil  No.  76    soil  No.  468 


Water 

Volatile  matter 

Insoluble  residue 

Ferric  oxide  (Fe203) 

Alumina  (AI2O3) 

Titanium  oxide  (Ti02) 

Manganese  oxide  (MnsOi). 

Lime  (CaO) 

Magnesia  (MgO) 

Potash  (K2O) 

Soda  (NaaO) 

Phosphoric  acid  (PjOs) 

Sulphur  trioxide  (SO3) 

Nitrogen  (N) 

Clay 

Fine  silt 

sat 

Fine  sand 

Coarse  sand 

Fine  gravel 


Per  cent 
J  13.  59 
20.01 
33.77 
7.00 
16.79 
1.80 
.07 
3.80 
.85  : 
.72  ! 

.10  ! 

2.18  I 

.45  : 

.65 
»5.24 
24.20 
18.  00 
30.70 

3.43    { 


Per  cent 

Per  cent 

1  33. 85 

i  11. 52 

11.79 

18.92 

32.17 

44.06 

8.36 

8.80 

11.25 

8.93 

2.00 

.02 

.14 

1.54 

2.32 

.87 

1.42 

.13 

.22 

.28 

.33 

.17 

.86 

.18 

.36 

.18 

.64 

«3.55 

1  Waikii  and  Makahalau  are  located  on  the  slopes  of  Mauna  Kea,  approximately  10  miles  across  the  plains 
from  the  Homestead  tract.  Because  of  their  altitudes  (3,500  to  4,500  feet)  they  are  subject  to  killing  frosts 
in  the  winter.  The  analyses  of  the  soils  of  these  two  districts  are  given  because  of  the  similarity  in  origin 
with  those  of  Waimea  proper  where  canna  is  being  grown. 

»  (5,  p.  SO).  «  (7,  p.  6).  *  (5,  p.  S3). 


Table  4  shows  that  the  soil  of  the  Homestead  tract  and  Waikii 
district  is  rather  low  in  clay,  a  large  portion  of  the  soil  being  distrib- 
uted between  the  fine-silt,  silt,  and  fine-sand  fractions. 

In  a  comparison  of  the  physical  properties  of  a  number  of  soil  types 
of  Hawaii,  McGeorge  (6)  found  that  the  Waimea  soils  have  the  lowest 
real  and  apparent  specific  gravity,  the  greatest  papillary  rise,  are 
among  the  lowest  in  rate  of{percolation,  and  require  the  highest  per- 
centage of  water  to  fill  the  interstitial  spaces. 


6  BULLETIN    57,   HAWAII   EXPERIMENT   STATION 

In  chemical  composition  (Table  4)  the  soils  of  the  district  differ 
markedly  from  most  of  the  other  soils  of  the  islands.  They  are  lower 
in  iron,  unusually  high  in  lime,  and  generally  high  in  phosphoric  acid. 
Soil  No.  474  from  the  Homestead  tract  is  well  supplied  with  potash 
also.  Soil  No.  76  from  Waikii  is  low  in  potash,  phosphoric  acid,  and 
nitrogen,  yet  it  is  said  to  produce  excellent  crops. 

The  differences  between  the  soils  of  Waimea  and  the  heavy  types 
of  the  islands  can  be  attributed  largely  to  their  origin  and  location. 
The  heavy  soils  are  largely  the  decomposition  products  of  lava  flows, 
partly  residual  and  partly  sedimentary,  resulting  from  erosion  of 
higher  areas.  The  properties  of  the  soils  of  Waimea  are  due  to  the 
surface  deposits  of  volcanic  ash  and  dust.  Moreover,  since  the  annual 
precipitation  at  Waimea  is  much  less  than  at  the  lower  levels  the 
soil  has  been  less  subjected  to  excessive  leaching  and  erosion,  as  is 
indicated  by  its  comparatively  high  content  of  lime.  The  loose,  deep 
soil  permits  ample  root  development  and  greatly  aids  the  growth  of  a 
crop.  Probably  the  plant-food  elements  which  are  tenaciously  held 
by  the  heavy  soils  are  readily  available  in  the  light  soils,  as  is  shown 
in  the  excellent  fertility  of  soil  No.  76,  which  is  very  low  in  potash, 
phosphoric  acid,  and  nitrogen. 

Mechanical  and  chemical  analyses  of  the  soils  of  the  Waimea  dis- 
trict are  too  few  to  justify  specific  conclusions  concerning  the  fertil- 
ity of  the  soils  as  a  whole.  No  general  survey  has  been  made,  and 
estimates  of  the  fertility  of  the  uncultivated  areas  must  be  based 
largely  on  the  range  grasses  growing  on  them.  Present  indications 
are  that  the  soils  of  nearly  all  the  homesteads  and  a  large  portion  of 
the  adjoining  Government  lands  of  the  Puukapu  district  are  adapted 
to  edible  canna. 

AGRICULTURAL  RETROSPECT 

The  first  series  of  homesteads  included  lots  Nos.  1  to  84,  with  an 
average  of  10  acres  per  homestead,  and  was  opened  in  1897.  The 
second  series  included  lots  Nos.  85  to  141,  with  an  average  of  40  acres 
per  homestead,  and  was  opened  in  1913.  This  area  extends  from  the 
village  of  Kamuela  eastward  along  the  foothills  of  the  Kohala  Range, 
and  comprises  some  of  the  best  land  in  the  district. 

The  district  was  thought  promising  as  an  agricultural  center  be- 
cause of  the  high  fertility  of  its  soil  and  the  variety  of  crops  doing 
well  there.  Many  kinds  of  vegetables,  especially  potatoes  and  cab- 
bage, were  apparently  well  adapted  to  the  region.  Of  the  field  crops, 
corn  did  exceptionally  well,  yielding  3,000  to  4,000  pounds  per  acre. 
Livestock  thrived  and  with  a  plentiful  supply  of  corn  and  nutritious 
pasturage  for  feeding  formed  the  nucleus  of  a  well-established  diver- 
sified agriculture.  Later,  however,  it  was  found  that  protracted 
periods  of  cold,  wet  weather,  and  strong  winds,  prevented  the  corn 
from  maturing,  and  that  blight  attacked  the  potato  crop.  High 
freight  rates  and  the  long  haul  to  the  Honolulu  market  prevented 
vegetable  growing  from  becoming  an  economic  success. 

Wheat  was  next  tried  but,  like  corn,  could  not  be  depended  upon 
to  mature.  Alfalfa  made  slow  growth  and  required  constant  care  and 
cultivation  to  keep  down  weeds.  Finally,  the  high  cost  of  importing 
grains  and  concentrated  feeds  prohibited  the  profitable  raising  of  pigs 
and  poultry.  Although  some  Japanese  truck  gardeners  are  still  rais- 
ing cabbage  and  potatoes  for  market,  and  in  places  corn  is  grown  as 
a  feed,  and  small  gardens  are  maintained  to  supply  the  family  with 


EDIBLE   CANNA   IN   WAIMEA   DISTRICT   OF   HAWAII  / 

sufficient  vegetables,  a  large  part  of  the  good  land  has  been  turned  back 
to  pasture,  and  agriculture  in  the  district  is  at  a  low  ebb.  What 
Waimea  needs  is  a  stable  field  crop  which  can  be  grown  throughout 
the  year  and  readily  converted  into  cash.  Edible  canna  would  seem 
to  meet  this  need  provided  the  crop  can  be  utilized  as  a  commercial 
source  of  starch. 

ADAPTATION  OF  EDIBLE  CANNA  TO  WAIMEA 

Of  all  the  places  in  Hawaii  where  edible  canna  has  been  observed, 
Waimea  seems  to  be  the  most  nearly  ideal  for  the  crop.  Observations 
on  small  plantings  showed  that  while  the  crop  yielded  as  well  as  other 
starch  crops  at  the  lower  levels,  it  made  outstandingly  high  yields 
only  at  the  higher  altitudes.  Dry,  windy  areas  caused  the  succulent 
tops  to  shrivel  prematurely,  and  alternately  wet  and  dry  conditions 
resulted  in  stunted  stalks  and  rootstocks.  Under  conditions  of  exces- 
sive moisture  the  crop  produced  vigorous  top  growth,  but  stunted 
rootstocks.  At  Waimea  growth  proceeds  notwithstanding  such 
adverse  conditions  as  high  winds  and  protracted  periods  of  cool,  cloudy 
weather  which  seriously  affect  other  crops,  and  the  plant  becomes 
luxuriant  with  the  return  of  favorable  conditions.  The  stalk  grows 
12  feet  high  at  Waimea,  whereas  it  seldom  exceeds  6  or  8  feet  in  most 
other  places.  The  stem  is  proportionately  greater  in  diameter  at 
Waimea,  and  the  rootstock  greatly  surpasses  in  size  and  yield  any 
grown  at  the  lower  levels. 

In  a  recent  publication  (9)  the  top  growth  of  edible  canna  was  shown 
to  live  longer  at  Waimea  than  at  the  central  station  in  Honolulu.  The 
vigor  and  longevity  of  the  maximum  period  of  activity  of  the  mature 
top  is  thought  to  be  one  of  the  chief  causes  of  the  increased  growth 
made  by  the  plant  at  Waimea.  The  temperature,  dews,  mists,  and 
light  rains  of  the  region  are  especially  favorable  to  the  crop.  The 
ill  effects  of  strong  winds — probably  the  only  serious  drawback  to  the 
crop — can  be  overcome  by  growing  windbreaks.  Edible  canna  is 
adapted  to  small -farrning  methods,  and  weeding  and  cultivating — 
the  greatest  single  expenses  in  growing  the  crop — can  be  done  by 
members  of  the  family  of  the  grower.  No  elaborate  machinery  is 
required  either  for  preparing  the  land  or  for  planting  and  cultivating 
the  crop. 

FIELD  PRACTICES 

Edible  canna  has  not  been  grown  at  Waimea  sufficiently  long  to 
warrant  definite  conclusions  as  to  the  best  agricultural  practices  with 
the  crop.  Climatic  and  soil  conditions  are  such  as  to  make  possible 
the  planting  of  corn  and  potatoes  every  month  of  the  year,  although 
February  and  August  are  regarded  as  the  most  favorable  months  for 
planting.  Edible  canna  plantings  of  different  seasons  have  shown  no 
outstanding  differences  in  growth.  The  scheme  of  continuous  plant- 
ing and  harvesting  has  its  advantages  since  it  permits  the  most  eco- 
nomical utilization  of  labor  and  equipment  during  the  entire  process 
of  field  production  and  manufacture  of  starch.  Before  such  a  plan 
is  established  on  a  large  scale,  however,  experiments  should  be  made 
to  determine  the  correlation  of  season  of  planting  to  yields. 

When  the  crop  is  to  be  grown  on  land  that  has  been  in  pasture  the 
heavy  sod  should  be  broken.  The  general  practice  is  to  plow  to  a 
depth  of  6  or  7  inches,  then  work  the  soil  down  with  a  disk  harrow, 
and  allow  it  to  stand  until  the  sod  begins  to  rot  and  new  shoots  appear. 


8 


BULLETIN    57,   HAWAII   EXPERIMENT  STATION 


A  second  plowing  is  then  made,  followed  by  harrowing,  and  in  another 
month  by  a  third  plowing  and  harrowing.  The  operation  is  repeated 
a  fourth  time  if  weeds  and  grass  roots  have  not  been  wholly  destroyed. 
Although  such  preparation  covers  three  or  four  months '  work,  any 
attempt  to  curtail  it  usually  results  in  depressed  yields  and  increased 
costs  in  cultivating  after  the  crop  is  planted.  Cultivated  land  requires 
usually  only  one  plowing  and  disking,  and  one  crop  closely  follows 
another.  The  light  soils  may  be  plowed  immediately  after  a  heavy 
rain  to  facilitate  rotting  of  the  weeds  and  grass. 

Continuous  cultivation  should  be  given  the  crop  until  it  attains  suf- 
ficient size  to  shade  out  weed  growth.  (Fig.  2.)  One  hoeing  is  usually 
enough  when  the  field  is  check  planted,  permitting  cross  cultivation. 
The  importance  of  clean  culture  in  the  early  stages  of  growth  of  edible 
canna  was  strikingly  demonstrated  in  a  portion  of  the  experimental 


Sffc*.         % 

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ty.Wfc          1 

1  M  5  ■ 

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-      mi      l  fi 

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v";V*. 

mimmi 

Elis9§ 

Fiq.  2.— A  two-month  weed  growth  in  a  field  of  canna 

plat  where  weeds  were  let  grow  for  the  first  seven  months.  Although 
this  portion  was  subsequently  weeded  and  given  the  same  treatment 
accorded  the  rest  of  the  plat,  it  yielded  20  tons  less  per  acre  at  20 
months  than  was  obtained  from  the  cultivated  portion.  Animal- 
drawn  cultivators  equipped  with  five  shovels  are  the  most  commonly 
used  types,  although  the  seven-tooth  type  is  being  introduced.  With 
the  latter  equipment  shallower  cultivation  is  possible,  the  long 
matted  grasses  are  more  readily  loosened,  and  the  shallow  root  growth 
of  the  canna  plant  is  less  likely  to  be  disturbed. 

The  expensive  process  of  hand  weeding  might  well  be  dispensed 
with  in  favor  of  sodium-arsenate  spray,  which  has  been  used  most 
effectively  in  the  Hamakua  and  Hilo  districts.  At  Waimea  the 
effectiveness  of  the  spray  might  be  lessened  somewhat  by  the  frequent 
mists  and  strong  winds.  The  spray  as  used  in  the  Hamakua  and 
Hilo  districts  is  made  as  follows  (10,  p.  54). 


EDIBLE   CANNA   IN   WAIMEA   DISTRICT   OF   HAWAII  9 

Boil  2  pounds  of  white  arsenic  and  0.42  pound  of  caustic  soda  in  water  until 
the  solution  becomes  clear.  This  is  made  up  to  1  gallon  with  water.  For  the 
succulent  plants  like  honohono,  dilute  to  25  gallons,  and  for  grasses  such  as 
Panicum,  dilute  to  10  gallons.  Soap  added  at  the  rate  of  1  pound  per  100  gallons 
of  spray  increases  the  effectiveness  of  the  spray. 

Poison  bait  should  be  used  to  control  cutworms  which  attack 
young  fields  of  canna  during  the  late  spring  and  early  summer.  A 
number  of  formulas  suitable  for  the  purpose  have  been  published  by 
the  station  (1,  p.  7). 

WINDBREAKS 

During  the  greater  part  of  the  year  the  Waimea  district  is  swept 
by  high  winds  which  shred  the  leaves  of  the  canna  plant,  draw  mois- 
ture from  the  soil,  and  otherwise  prevent  normal  growth.  Crops 
which  are  protected  by  windbreaks  make  more  vigorous  and  thrifty 
growth  than  do  those  left  exposed  in  the  open. 

Trees  and  plants  which  are  used  for  windbreaks  in  the  Waimea 
district  include  eucalyptus  (fig.  3),  black  wattle,  Monterey  cypress 


Fig.  3.— Eucalyptus  windbreak,  showing  paucity  of  foliage  near  the  base 

(fig.  4),  castor-bean  trees  (fig.  5),  and  the  banana  plant,  and  combi- 
nations of  these.  The  eucalyptus  is  quick  growing,  attains  sufficient 
height  in  three  or  four  years  to  protect  a  field,  and  has  the  additional 
value  of  supplying  fairly  good  fence  posts  and  firewood  when  the  trees 
are  thinned  out  or  pruned.  The  black  wattle  also  is  quick  growing 
and  furnishes  more  durable  posts  than  the  eucalyptus,  but  bends 
with  the  wind  to  such  an  extent  as  to  utilize  too  much  ground.  The 
Monterey  cypress  requires  10  to  12  years  to  attain  a  height  sufficient 
to  protect  a  field,  but  makes  an  ideal  windbreak  when  it  is  planted  in 
combination  with  eucalyptus  or  black  wattle.  The  Monterey 
cypress  makes  straight  growth,  attains  good  height,  and  covers  com- 
paratively little  area.  The  lower  branches  of  the  eucalyptus  die 
when  the  tree  is  about  15  feet  high,  and  the  spaces  left  by  these  should 
be  filled  by  the  slow-growing  cypress.  After  10  or  12  years,  when  the 
faster  growing  trees  are  removed  for  fence  posts  or  firewood,  the  cypress 
can  carry  on  alone.     (Fig.  6.)    Any  variety  of  banana  plant  which  does 

83065—28 2 


10 


BULLETIN    57,    HAWAII   EXPERIMENT  STATION 


not  grow  over  8  feet  high  can  be  planted  midway  between  the  more 
permanent  windbreaks  to  protect  a  field.  The  banana  plant  makes 
short,  compact  growth  and  is  of  additional  value  in  producing  fruit. 
Castor-bean  trees  afford  protection  in  less  time  than  any  of  the  other 
trees  now  used  for  windbreaks.     They  protect  a  greater  area  than 


Fig.  4.— An  old  Monterey  cypress  windbreak.  Note  the  low-branching  and  dense  foliage;  also 
the  lack  of  top  branches  on  the  windward  side.  The  fog  shown  in  the  center  of  the  picture  is 
characteristic  of  Waimea 

does  the  banana  plant  but  less  than  the  eucalyptus-cypress  combina- 
tion, and  like  the  banana  are  usually  planted  midway  between  the 
more  permanent  windbreaks  at  the  edges  of  the  field.  Probably  the 
best  windbreak  for  the  Waimea  district  is  one  consisting  of  a  row  of 


Fig.  5.— A  castor-bean  windbreak.    Note  the  low,  dense  growth  which  makes  the  tree  desirable  for 

secondary  windbreaks 

Monterey  cypress  planted  close  to  the  fence  on  the  windward  side  of 
the  field,  to  the  lee  of  which  are  two  or  three  rows  of  eucalyptus.  The 
cypress  should  be  planted  10  feet  apart  and  the  eucalyptus  10  feet 
apart.  If  further  protection  is  necessary  the  windbreak  across  the 
middle  of  the  field  should  consist  of  castor-bean  trees  or  banana  plants. 


EDIBLE   CANNA   IN   WAIMEA   DISTRICT   OF   HAWAII 


11 


EXPERIMENTS  WITH  EDIBLE  CANNA 

Experiments  were  made  to  determine  the  best  types  of  rootstocks 
to  use  for  planting,  the  effect  of  preliminary  treatment  to  prevent  rot- 
ting of  the  seed,  the  depth  of  planting,  the  number  of  seed  to  plant 
per  hill,  the  feasibility  of  mulching  with  canna  tops,  the  time  of 
applying  fertilizer,  and  the  best  age  at  which  to  harvest  the  crop. 
The  crop  occupied  34  plats,  comprising  a  total  of  4.8  acres  of  land. 

The  experiments  were  begun  in  July,  1924,  on  homestead  No.  98, 
where  the  soil  is  deep,  porous,  and  representative  of  the  best  in 
Waimea.  A  good  windbreak  protects  the  crop  from  the  trade 
winds.  The  field  was  inspected  September  4,  and  the  percentage  of 
nongermination  was  determined  for  each  plat.  The  misses  were 
replaced  in  all  instances  except  on  the  plats  used  for  rootstock- 
selection  tests,  for  which  acre  yields  were  computed  from  the  actual 


wm 


mi 


*v5nfe 


Fig.  6. — Combination  windbreak  of  eucalyptus  and  Monterey  cypress.    The  cypress  is  sufficiently 
high  to  permit  removal  of  the  eucalyptus 

number  of  hills  dug.  The  crop  was  harvested  between  March  22 
and  March  30,  1926,  20.5  months  after  planting.  Visits  were  made 
to  the  plats  at  intervals  of  two  months,  notes  were  taken  on  general 
growth,  and  some  individual  hills  were  dug  to  study  the  progressive 
development  of  the  plant. 

METHODS  OF  INVESTIGATION 

In  a  previous  bulletin  (9)  a  description  of  the  nature  of  growth  of 
edible  canna  was  given,  together  with  a  brief  outline  of  the  methods 
of  investigation  devised  to  study  the  progressive  growth  of  the  hill. 
Since  these  methods  have  been  found  useful  in  the  present  investi- 
gation a  somewhat  detailed  discussion  is  included. 

GENEALOGIZATION 

In  this  study  the  hill  was  carefully  dug  to  remove  the  entire  clump 
of  rootstocks  unbroken.  The  clump  was  then  carefully  broken  in  half 
to  locate  the  original  seed  and  the  rootstock  or  rootstocks  directly 


12  BULLETIN   57,   HAWAII  EXPERIMENT  STATION 

attached  to  it,  which  are  termed  the  first  generation.  The  rootstocks 
directly  attached  to  the  first  generation  are  the  second  generation, 
and  so  on.  Thus,  a  hill  can  be  dug  after  12  months  and  the  progressive 
stages  of  growth  traced  from  the  original  seed  rootstock. 

CLASSIFICATION 

In  classifying  the  rootstocks  in  a  hill  they  are  grouped  as  (1)  dor- 
mant, (2)  mature,  and  (3)  immature.  The  immature  group  is  further 
divided  into  (a)  rootstocks  with  little  or  no  meristematic  growth; 
and  (b)  rootstocks  with  meristematic  growth.  Since  the  transition 
from  immaturity  tofmaturity  and  thence  to  dormancy  is  rather 
gradual,  it  is  deemed  necessary  to  define  the  limits  of  each  group  in 
some  detail. 

The  dormant  group  comprises  plants  on  which  the  leaves  have 
died  and  the  stems  have  or  have  not  yet  shriveled. 

In  the  mature  group  the  oldest  members  still  bear  a  green  leaf  at 
the  apex,  but  the  lower  leaves  are  dead.  The  lower  leaves  are  begin- 
ning to  shrivel  at  the  edges  on  the  younger  members  and  growth 
of  new  leaves  at  the  apex  has  practically  ceased.  A  stalk  in  the 
bud  or  bloom  stage  is  placed  in  the  mature  group  even  though  the 
basal  leaves  are  still  green. 

The  stalks  of  the  oldest  members  of  the  immature  3a  group  have 
attained  nearly  full  height  with  the  basal  leaves  still  green,  whereas 
one  leaf  is  beginning  to  unfold  on  the  youngest  members. 

The  oldest  members  of  the  immature  3b  group  have  not  yet  begun 
to  develop  stalks,  whereas  the  youngest  members  have  just  emerged 
from  the  bud  stage.  All  members  of  this  group  are  thus  young 
" spikes."  They  are  fresh  in  appearance  and  the  basal  scales  show 
little  sign  of  shrivelling  at  the  edges.  They  are  deep  purple  whereas 
the  epidermis  of  the  rootstock  is  pink  at  the  apex. 

Some  spike  rootstocks,  the  stalks  of  which  fail  to  develop,  remain 
in  every  hill.  Usually  either  the  parent  or  the  offspring  has  a  stalk 
and  the  "spike"  is  placed  in  the  next  younger  group  than  the  parent 
or  the  next  older  group  than  the  offspring.  A  comparatively  small 
"spike"  which  is  attached  to  a  mature  rootstock  and  bears  no  off- 
spring is  classed  as  a  part  of  the  parent  rootstock. 

The  division  between  the  youngest  members  of  the  immature 
group  (3b  stage),  and  developing  buds  is  necessarily  inexact  and 
relative.  This  division  can  not  be  based  on  size,  which  varies  with 
the  field  and  the  stage  of  maturity.  Usually,  however,  the  uncer- 
tainty is  small  when  the  general  rule  is  followed  to  classify  as  buds 
all  those  which  have  not  become  "sizeable"  and  have  no  definite 
"rounding  in"  at  the  attachment  with  the  parent. 

APPLICATION  OF  METHODS 

Application  of  the  above-outlined  methods  to  edible  canna  of 
various  ages  and  grown  under  widely  different  climatic  conditions, 
has  demonstrated  that  they  have  certain  definite  limitations.  Gene- 
alogization,  while  comparatively  simple  in  the  first  8  to  10  months 
of  growth,  is  rendered  practically  impossible  with  a  hill  18  to  20 
months  old,  by  the  death  of  the  original  stalks  and  the  growth  of 
one  line  of  rootstocks  over  another,  and  its  use  is  consequently 
restricted  to  determining  the  early  tendencies  of  growth  of  individual 
hills. 


EDIBLE   CANNA  IN  WAIMEA  DISTEICT  OP  HAWAII 


13 


In  classifying  plants  the  maturity  of  the  stalks  is  taken  as  the 
measure  of  maturity  of  the  rootstock.  This  is  not  always  the  case 
since  often  stalk  growth  is  delayed  and  the  rootstock  may  be  old  in 
appearance  while  the  stalk  is  young  and  growing  vigorously.  Again, 
the  lower  leaves  of  a  stalk  may  shrivel  from  excessive  heat,  drought, 
or  wind,  and  thus  be  classed  as  Group  2,  whereas  the  apical  portion 
of  the  top  is  still  immature  and  be  classed  as  Group  3a.  Subsequent 
findings,  however,  show  a  definite  correlation  between  classification 
and  the  yields  from  monthly  harvests  on  0.1-acre  plats  and  a  much 
greater  insight  into  the  habit  of  growth  of  the  plant  than  would 
have  been  possible  with  only  general  observations  and  notes. 

RESULTS  OF  GENEALOGIZATION 

Results  of  genealogization  failed  to  show  any  consistent  differences 
in  the  several  plats  because  of  the  very  large  variations  between  the 
individual  hills.  For  this  same  reason,  however,  the  method  was  of 
value  in  selecting  individual  hills  to  determine  desirable  tendencies 
of  growth  in  the  hill,  as  is  illustrated  in  Table  5. 

Table  5. — Comparison  in  generation  of  two  hills,  each  10  months  old,  of  opposite 

tendencies 


Generation 

Number 
of  root- 
stocks 

Weight 
of  root- 
stocks 

Average 
weight 

per  root- 
stock 

Number 
of  stalks 

Number 
of  spikes 

Hill  No.  l: 

1 

2 
7 
12 
8 
2 

Pounds 

Pounds 

2 
6 
6 
3 
0 

0 

2 

0 

3 

6 

4 

5 

5. 

2 

Total.. 

31 

13.5 

0.44 

17 

13 

Hill  No.  2: 

1 

2. 

3 

4 

5 

6 

7 

Total.. 


1 

j 

1 

1 
3 
5 
3 

3 

6 

1 

4 

1 

4 

4 

1 

:::::::::: 

20 


20.6 


The  hills  represent  two  extremes,  one  tending  to  stool  rapidly  and 
the  other  slowly.  At  the  end  of  the  third  generation,  hill  No.  1  had 
21  rootstocks  in  contrast  with  hill  No.  2,  which  had  only  5.  As  a 
result  of  the  extreme  tendencies,  hill  No.  1  had  stunted  rootstocks, 
whereas  hill  No.  2  had  exceptionally  large  rootstocks  which  were 
proportionally  greater  in  total  weight  and  more  desirable  for  starch 
manufacture. 

The  fact  that  there  was  a  large  number  of  spikes  in  hill  No.  1,  a 
small  number  in  hill  No.  2,  and  a  similar  number  of  developed  stalks 
in  both  hills,  would  seem  to  show  that  the  purpose  of  the  spikes  is 
to  serve  as  storage  organs.  The  death  of  the  meristem  of  many  of 
the  spikes  was  at  first  thought  to  be  the  cause  of  their  failure  to  de- 
velop stalks,  but  death  more  probably  was  the  result  of  their  long 
exposure  in  a  dormant  state. 


14 


BULLETIN    57,   HAWAII   EXPERIMENT   STATION 


SELECTION  OF  ROOTSTOCKS  FOR  "SEED" 


A  hill  of  canna  contains  a  heterogeneous  lot  of  rootstocks.     A 
single  hill  18  months  old  contains  rootstocks  which  have  been  dormant 


Fig.  7.— Subsurface  types  of  canna  seed:  A,  Second  generation— note  tapering  shape  and  location  of 
buds;  B,  first  generation  with  only  one  bud  remaining;  C,  first  generation  with  eight  buds 

for  nearly  a  year  and  others  which  are  just  developing,  the  different 
types  varying  in  weight  from  a  few  ounces  to  more  than  2  pounds. 


Fig.  8.— Immature  surface  types  of  canna  seed:  A,  Well-developed  attached  spikes;  B,  small 
attached  spikes;  C,  buds;  D,  no  visible  buds 

Although  the  transition  from  one  type  of  roots tock  to  another  is 
gradual,  the  entire  hill  can  be  divided  into  a  number  of  groups,  each 
of  which  has  distinct  characteristics. 


EDIBLE    CANNA   IN   WAIMEA   DISTRICT   OF   HAWAII 


15 


To  determine  the  relative  desirability  of  the  different  types  of  root- 
stocks  for  seed  purposes,  a  portion  of  an  18-month-old  field  of  canna 
was  dug  and  the  rootstocks  were  divided  into  six  groups  having  the 
following  characteristics : 

Subsurface  type  (fig.  7). — Rootstocks  of  the  subsurface  type  are 
small  and  cylindrical  to  tapering  and  constitute  the  first  two  genera- 
tions. They  exist  in  a  dormant  state  in  a  hill  12  months  old  and  their 
stems  are  dead.  The  rootstock  grows  beneath  the  surface  of  the  soil 
in  contrast  with  the  surface  types.  The  subsurface  type  has  short 
internodes  and  may  bear  buds  at  practically  every  node  from  base 
to  apex.  As  many  as  10  have  been  observed  on  a  single  rootstock, 
although  2  and  3  are  the  rule.  The  buds,  which  are  usually  small, 
remain  dormant  until  the  newer  growth  of  the  hill  is  checked. 

Immature  rootstocks,  surface  type  (figs.  8  and  9). — This  type  grows 
largely  above  ground  and  is  oval  shaped.     The  buds  have  large  basal 


Fig.  9.— Base  of  hill  of  canna  5  months  old 

attachments  to  the  parent  and  appear  only  near  the  apex  of  the  root- 
stock.  Usually  two  buds  are  seen,  but  occasionally  a  third  appears 
which  ordinarily  does  not  develop.  On  some  rootstocks  of  this 
group  one  bud  has  already  reached  the  rootstock  stage  and  has  been 
removed,  whereas  on  the  youngest  members  only  one  bud  has  made 
its  appearance.  (Fig.  10.)  The  stalks  of  this  group  are  immature  and 
sometimes  entirely  undeveloped  spikes.  The  group  is  further  sub- 
divided into  (1)  large  rootstocks  constituting  the  most  vigorous  and 
newest  growth  of  the  hill;  and  (2)  small  rootstocks  constituting  the 
secondary  growth.  (Fig.  11,  A  and  B.)  The  secondary  growth  appears 
during  the  later  stages  of  growth  of  the  hill,  or  after  the  vigorous 
growth  has  been  stopped  by  adverse  weather  conditions. 

Attached  spike. — This  type  is  like  the  immature  surface  type  except 
that  one  or  both  of  the  buds  have  developed  into  spikes  which  are 
not  of  sufficient  size  to  be  called  rootstocks.  For  seed  purposes  the 
spike  is  left  attached  to  the  parent. 


16 


BULLETIN    57,   HAWAII   EXPERIMENT  STATION 


Detached  spike. — In  this  type  the  spike  is  detached  from  the  parent 
rootstock  and  used  for  seed. 


Fio.  10.— Bud  formation  on  immature  surface  type  of  canna  root- 
stock.  The  buds  c  and  6  constitute  the  vigorous  primary  growth 
of  the  hill;  a  usually  remains  dormant  or  produces  a  small  second- 
ary growth 


Fig.  11.— Secondary  types  of  canna  seed:  A,  Small,  primary  growth;  B,  C,  and  D,  secondary  growth 

Mature  rootstocJcs  with  dormant  buds. — Usually  one  or  two  buds  in 
this  type  have  developed  into  rootstocks,  and  the  remaining  bud  or 
buds  exist  in  a  dormant  condition  for  many  months.     The  parent 


EDIBLE    CANNA   IN   WAIMEA   DISTRICT   OF   HAWAII 


17 


stalk  if  developed  must  be  either  mature  or  dormant.  To  this  type 
also  belong  mature  rootstocks,  the  stems  of  which  have  never 
developed. 

Rootstoclcs  with  no  visible  buds. — In  this  group  are  placed  the  older 
rootstocks  the  visible  buds  of  which  have  already  developed  into 
offspring. 

The  several  types  of  seed  were  planted  in  the  experimental  field 
July  10,  1924,  and  the  resulting  crop  was  harvested  March  25,  1926. 
The  hills  were  spaced  4  by  4  feet  apart.  Single  hills  were  dug  from 
the  several  plats  from  time  to  time  for  classification.  Table  6  com- 
pares the  yields  and  weights  of  single  hills  dug  from  the  different 
plats  at  bimonthly  intervals. 

Table  6. — Comparison  in  yield  and  weight  of  single  hills  dug  from  the  seed- 
selection  plats  at  bimonthly  intervals 


Plat 
No. 

Kind  of  seed 

Date  of  harvest 

Number 
of  root- 
stocks 
per  hill 

Weight 
of  hill 

Average 
weight 

per  root- 
stock 

8 

Subsurface  rootstock 

February,  1925 

April,  1925 

June,  1925 

22.0 
22.0 
19.0 
•    27.0 
56.6 
23.0 
26.0 
28.0 
41.0 
57.7 
18.0 
31.0 

Pounds 
14.5 
15.3 
14.1 
21.7 
36.5 
14.0 
19.5 
22.8 
35.2 
42.1 
11.0 
13.5 

Pound 
0.66 

Immature  rootstock  (two  buds) 

.70 
.74 

1? 

August,  1925 

February,  1926  »— 

February,  1925 

April,  1925 

June,  1925.. 

.80 
.65 
.61 

Mature  rootstock  (dormant  bud1* 

.75 
.81 

14 

August,  1925 

February,  1926  »„. 

February,  1925 

April,  1925 

June,  1925 

.86 
.73 
.81 

Detached  spike.. 

.44 

IS 

August,  1925 

February,  1926  i... 

February,  1925 

April,  1925 

June,  1925 

48.0 
56.6 
12.0 

31.6 

36.7 

7.n 

.66 
.65 

Attached  spike  - 

17.0  1            6.5                 .38 
23.0              15.  f)                  .65 

16 

August,  1925 

February,  1926  »„. 

February,  1925 

April,  1925 

June,  1925.. 

August,  1925 

February,  1926  L.. 

February, 1925 

April,  1925 

June,  1925 

36.0 
39.3 
20.0 
23.0 
26.0 
44.0 
50.8 
15.0 

18.0 
25.4 
10.0 
12.0 
17.0 
29.0 
33.9 
6.5 

.50 
.65 
.50 

17 

Immature  rootstock  (secondary) 

.5k 
65 
66 
66 

.a 

18.0  ,            7.5                 .42 
19.0  :           13.8                 .73 

August,  1925 

February,  1926  »___ 

29.3 

18.0 

.62 

1  Average  of  four  hills. 

Table  6  shows  clearly  the  initial  depressing  effect  of  two  types  of 
seed,  namely,  the  detached  spike  and  the  secondary  immature  root- 
stock.  It  was  not  until  June,  11  months  after  planting,  that  these 
two  plats  produced  a  vigorous  growth.  The  differences  in  the  results 
from  the  other  types  of  seed  are  not  pronounced  and  might  easily  be 
accounted  for  by  individual  hill  variation. 

Taken  as  a  whole  the  period  from  February  to  June  was  one  of  slow 
growth  with  a  general  tendency  toward  increase  in  average  weight. 
Beginning  with  August,  there  is  apparent  a  sudden  renewal  of  growth 
resulting  in  large  increases  in  both  number  of  rootstocks  and  weight 
of  the  hill.  With  the  exception  of  plat  8,  the  six  months  period  from 
August  to  February,  1926,  was  one  of  comparatively  slow  growrth. 

83065—28 3 


18 


BULLETIN    57,   HAWAII   EXPERIMENT   STATION 


This  irregular  nature  of  growth  of  the  edible  canna  is  again  discussed 
in  a  later  section  (p.  31). 

Table  7  gives  the  yields  of  the  different  kinds  of  planting  stock 
tested  and  the  proportion  failing  to  germinate. 

Table  7. — Yields  and  nongermination  of  different  types  of  canna  seed 


Plat 
No. 

Kind  of  seed 

Area  of 
plat 

Propor- 
tion of 

seed  fail- 
ing to 

germinate 

Number 
of  hills 

har- 
vested 

Gross 

yield  per 

acre 

Net  yield 
per  acre 

8 

Subsurface  rootstock 

^4crc 
0.100 
.100 
.100 
.025 
.025 
.025 
.025 
.025 

Per  cent 
8.5 
77.7 
2.7 
16.9 
15.4 
32.3 
9.2 
9.2 

217 

Tons 
41.6 

Tons 
37  3 

9 

Mature  rootstock  (no  visible  bud) 

12 

Immature  rootstock  (two  buds) 

253 
53 
55 
47 
59 
58 

43.  6  1            39. 1 
43  7  ;            39  2 

»  13 

Immature  rootstock  (one  bud). 

14 

Mature  rootstack  (dormant  bud).. 

38.4  j            34.4 

15 

Detached  spike 

34  1               30  5 

16 

17 

A t tached  spike 

40  5              36  3 

Immature  rootstock  (secondary) 

32  6 

1  In  most  of  this  seed  one  bud  had  developed  into  a  rootstock. 

It  may  be  concluded  from  Table  7  that  the  large,  immature  root- 
stocks  with  two  buds  make  the  most  desirable  seed  for  planting. 
Large,  immature  rootstocks  with  one  bud  are  equal  in  point  of  yield 
to  those  having  two  buds,  but  rather  low  in  germination.  Next  in 
point  of  yield  is  the  subsurface  type,  closely  followed  by  the  attached 
spike.  With  respect  to  germination  these  two  types  are  decidedly 
superior  to  the  immature  rootstock  with  one  bud.  The  mature 
rootstocks  with  dormant  buds  are  somewhat  less  valuable  in  yield 
than  the  preceding  types  and  rather  low  in  germination.  Detached 
spikes  are  too  uncertain  in  germination  and  too  low  in  yield  to  make 
desirable  seed.  Very  small,  immature  rootstocks,  although  fair  in 
germination,  rank  lowest  in  poin,t  of  yield. 

The  rate  of  germination  is  dependent  more  upon  the  condition  of 
the  buds  than  on  the  type  of  seed.  Buds  on  the  subsurface  type  of 
rootstock  usually  are  in  good  condition  at  the  time  of  digging.  A 
rootstock  of  this  type  bearing  at  least  two  buds  is  always  preferable 
to  a  seed  with  one  bud,  because  the  buds  at  best  are  small,  succulent, 
And  easily  damaged,  and  the  percentage  of  germination  tends  to  be 
low  when  only  one  bud  is  used.  The  buds  of  the  immature  type  do 
not  project  from  the  parent  seed  sufficiently  to  be  easily  broken  off, 
and,  due  to  their  freshness,  they  are  seldom  worm-eaten.  The  dor- 
mant buds  on  older  rootstocks  have  been  more  or  less  exposed  to 
worm  and  other  injury  and  are  not  therefore  as  certain  to  germinate 
as  are  those  of  the  types  previously  discussed.  The  attached  spikes 
have  many  possibilities  of  germination.  The  terminal  spike  may 
(grow;  frequently  the  two  "top"  buds,  one  on  each  side  of  the  spike, 
develop.  In  addition,  a  bud  on  the  parent  seed  may  be  capable  of 
development.  Usually  this  type  of  seed  is  fully  equal  in  point  of 
germination  to  the  two  primary  buds.  The  detached  spike  usually 
has  no  visible  buds  and  germination  proceeds  from  the  dormant  top 


EDIBLE    CANXA    IX    WAIMEA   DISTRICT    OF   HAWAII  19 

buds.     The  buds  on  the  very  small,  immature  seed  are  of  the  primary 
type  and  are  usually  in  good  condition. 

Obviously,  no  single  set  of  experiments  over  one  year  can  do  more 
than  indicate  the  most  desirable  type  of  seed  for  planting.  Many 
unknown  and  variable  factors  remain  for  determination,  even  when 
the  soil  is  uniform,  the  culture  perfect,  the  weather  normal,  and  the 
crop  of  the  proper  age  for  harvesting.  Whether  edible  canna  is 
sufficiently  pure  in  type  to  obviate  the  effect  of  individual  variation 
in  the  seed  is  unknown.  The  ultimate  result  of  continuously  planting 
one  kind  or  size  of  seed  to  the  exclusion  of  all  others  must  be  deter- 
mined. The  economic  phases  of  the  problem  also  await  solution.  A 
type  of  seed  proving  more  desirable  than  others  through  repeated 
experiments  may  not  be  available  during  certain  seasons  of  the  year 
or  stages  of  maturity  of  the  crop.  For  example,  many  large,  imma- 
ture rootstocks  with  developing  buds  can  be  found  during  certain 
seasons  with  practically  no  attached  spikes.  Two  months  later 
these  buds  will  have  nearly  all  developed  into  spikes,  with  scarcely 
any  developing  buds.  At  other  times  neither  spike  nor  bud  is  present 
in  large  numbers.  Dependence  upon  one  particular  type  of  seed 
would  probably  be  impractical. 

Results  of  experiments  in  seed  selection  point  to  the  elimination 
of  at  least  three  types — those  with  no  visible  buds,  the  small  detached 
spikes,  and  the  very  small  secondary  kinds.  With  the  elimination 
also  of  the  dormant  buds  as  questionable  because  of  their  long 
exposure  to  weather  and  insects  the  only  desirable  types  remaining 
are  the  subsurface,  the  immature  with  one  or  two  buds,  and  the 
attached  spikes. 

As  the  hill  advances  in  age  the  proportion  of  desirable  seed  decreases. 
This  decrease  is  due  partly  to  the  development  of  buds  on  the  older 
rootstocks,  but  mostly  to  injury  to  the  buds.  On  the  other  hand, 
nearly  every  rootstock  is  desirable  for  seed  in  a  field  where  the  fourth 
and  fifth  generations  (usually  at  nine  months)  are  developing.  This 
fact  suggests  the  possibility  of  digging  young  fields  for  seed  purposes. 
The  relative  desirability  of  planting  one  carefully  selected  seed  piece 
per  hill  or  two  less  carefully  selected  seed  can  be  determined  only  after 
data  are  obtainable  on  relative  yields,  percentages  of  germination,  and 
cost  of  seed. 

TREATMENT  OF  "SEED" 

Rotted  seed  may  be  found  in  normal  hills,  but  more  frequently  it 
is  associated  with  particularly  small  or  stunted  hills.  To  determine 
the  effect  of  chemical  treatment  on  rot,  three  types  of  freshly  dug 
canna  rootstocks  were  exposed  to  the  sunlight  for  24  hours  and  then 
soaked  in  solutions  of  copper  sulphate  or  mercuric  chloride.  The 
rootstocks  were  then  dried  in  the  sun  for  an  hour  and  placed  three  per 
hill  in  the  field.  In  order  to  produce  conditions  favorable  for  rot,  the 
field  was  irrigated  three  times  a  week.  The  resulting  crop  was  har- 
vested after  two  months  when  the  most  advanced  stalks  were  about 
3  feet  hisrh.  The  results  of  treating  seed  with  copper  sulphate  are 
given  in  Table  8. 


20 


BULLETIN    57,    HAWAII   EXPERIMENT   STATION 


Table  8. — Effect  of  copper  sulphate  upon  germination  and  rotting  of  edible  canna 

rootstocks 


Kind  of  seed 

Treatment 

Propor- 
tion of 
rot  in 
germi- 
nated 
seed 

Number 
of  seed 
germi- 
nated 

Number 
of  stalks 

Appearance 
of  stalks 

CuS04,  5  per  cent  for  15  minutes 

CuSO<,  5  per  cent  for  45  minutes 

CuSO<,  10  per  cent  for  15  minutes 

CuSCh,  10  per  cent  for  45  minutes 

H 

3 

2 
2 
0 
3 
1 
0 
0 
0 
3 

2 
1 
0 
3 

9 
8 
7 
0 
9 
2 
0 
0 
0 
6 
4 
9 
7 
0 
9 

Good. 

Poor. 
Fair. 

Control  (no  treatment) 

0 

Attached  spike 

CuS04,  5  per  cent  for  15  minutes 

CuS04,  5  per  cent  for  45  minutes..  .. 

Medium. 

CuS04,  10  per  cent  for  15  minutes 

CuS04,  10  per  cent  for  45  minutes 

Control  (no  treatment) 

H 

% 
H 

Immature  rootstock, 
two  buds. 

CuS04,  5  per  cent  for  15  minutes 

CUSO4,  5  per  cent  for  45  minutes 

CuS04,  10  per  cent  for  15  minutes 

CuS04,  10  per  cent  for  45  minutes 

Good. 

Fair. 

Poor. 

Control  (no  treatment) 

H 

Excellent. 

Copper  sulphate  did  not  prevent  rotting  of  the  seed.  In  fact,  the 
treatment  apparently  increased  the  tendency  to  rot.  Even  the 
mildest  treatment  depressed  germination.  Of  the  three  kinds  of 
seed  tested,  the  subsurface  type  was  the  most  resistant  both  to  the 
disinfectant  and  the  rot.  Partial  rotting  of  the  seed  apparently 
had  no  effect  on  the  vigor  of  the  resulting  plant,  but  where  rot  had 
penetrated  to  the  portion  of  the  seed  adjoining  the  developing  bud, 
there  was  a  marked  stunting  of  the  stalks  and  a  tendency  toward 
profuse  development  of  buds.  Examination  of  the  rotted  seed 
showed  somewhat  darkened  and  watery  tissue,  nearly  all  of  which 
was  worm-infested.  Although  the  worms  feed  mostly  on  decayed 
tissue  they  probably  increased  the  rate  of  decay  by  opening  fresh 
tissue.  Rotting  proceeded  from  the  base  of  the  seed  where  it  had 
been  attached  to  the  parent,  or  along  the  side  from  which  an  off- 
spring had  been  removed.     (Fig.  12.) 

Immersing  lots  of  seed  similar  to  those  treated  with  copper  sulphate 
in  mercuric  chloride  in  concentrations  of  8  and  16  grams  per  gallon 
for  periods  of  15  and  45  minutes  for  each  concentration  did  not  have 
any  toxic  effect  on  germination  or  prevent  rot. 

Although  edible  canna  rootstocks  remain  dormant  and  in  excellent 
condition  when  they  are  left  undug  in  the  ground  for  12  months 
(20  months  after  planting),  they  deteriorate  rapidly  upon  exposure 
after  digging.  One  of  the  causes  of  deterioration  after  digging  may 
be  discovered  by  evacuating  a  rootstock  under  water.  Bubbles 
will  rise  from  all  parts  of  the  surface  and  the  rootstock  will  increase 
8  to  10  per  cent  in  weight.  The  moisture  of  freshly  dug  rootstocks 
evaporates  rapidly  through  the  epidermis,  and  the  resulting  influx 
of  air  opens  the  way  for  fermentation  and  decay.  Since  fermenta- 
tion and  destruction  of  sugars  take  place  in  15  to  21  days  (9),  pro- 
longed storage  of  the  seed  tends  only  to  increase  rot  and  to  reduce 
vitality  of  the  buds. 

Frequent  observations  have  shown  that  the  original  seed  of  a  hill 
18  months  old  is  in  excellent  condition.  At  times  rot  appeared  to 
have  begun  and  to  have  partly  destroyed  the  seed,  while  the  remainder 


EDIBLE    CANNA    IN    WAIMEA    DISTRICT    OF   HAWAII  21 

was  quite  sound.  This  was  probably  due  to  the  fact  that  after  the 
bud  has  developed  a  stem  of  good  size  the  seed  becomes  an  integral 
part  of  the  plant  and  possesses  all  the  rot-resistant  qualities  of  the 
undug  rootstock. 

Rotting  of  the  seed  apparently  does  not  injure  the  developing  bud 
or  the  resulting  plant  when  germination  has  not  been  unduly  de- 
layed. A  canna  rootstock  weighing  8  to  12  ounces  contains  much 
more  plant  food  than  is  needed  for  bud  development,  and  rot  usually 
begins  at  the  base  of  the  seed  at  its  juncture  with  the  parent,  which 
part  is  farthest  from  the  bud.  The  younger  portions  of  the  root- 
stock  are  much  less  susceptible  to  rot  than  the  older  portions.  Hence, 
a  healthy  bud  usually  has  sufficient  time  and  plant  food  to  develop 
normally  before  rot  can  penetrate  to  the  upper  portions  of  the  seed. 
A  faulty  bud  as  the  result  of  which  germination  is  unduly  delayed 


Fig.  12.— Rotting  of  canna  seed  after  two  months  in  the  ground.  The  seed  was  dug,  cut  in  half,  and 
exposed  to  the  air  for  15  minutes.  A,  Sound  seed  which  had  developed  a  number  of  stems;  B, 
rotted  seed — rot  had  penetrated  throughout  the  parent  seed,  but  had  not  entered  the  developing 
bud;  C,  partly  rotted  seed,  showing  the  progress  of  rot  upward  from  the  base  of  the  rootstock— 
note  the  worm  infestation  at  the  base 

will  probably  be  found  to  be  the  cause  of  a  stunted  hill  resulting 
from  a  rotted  seed.  Extreme  conditions  of  moisture  or  drought 
facilitate  decay.  Seed  which  grows  close  to  the  surface  of  the  ground 
or  which  is  partly  exposed  is  susceptible  to  rot.  Fully  90  per  cent 
of  all  the  chemically  treated  and  untreated  lots  of  seed  rotted  to 
some  extent  in  the  soil  which  was  kept  excessively  moist  in  the 
experiments  for  rot  control. 

Results  of  experiments  conducted  at  the  station  would  seem  to 
indicate  that  seed  for  planting  should  be  selected  from  freshly  dug 
rootstocks.  It  should  then  be  place:!  in  bags  for  three  or  four  days 
where  a  free  circulation  of  air  will  heal  the  cut  surfaces.  The  seed 
should  always  be  carefully  handled.  Selection  and  bagging  should 
be  done  in  the  field.  The  tender  buds  are  very  likely  to  be  bruised 
when  the  seed  is  selected  at  the  mill. 


22 


BULLETIN    57,    HAWAII   EXPERIMENT   STATION 


DEPTH  OF  PLANTING 

The  rootstocks  of  the  edible  canna  are  inclined  to  grow  at  or 
above  the  surface  of  the  ground.  (Fig.  13.)  Many  of  them  in  a  field 
12  months  old  will  be  found  growing  several  inches  above  the  surface 
with  no  root  system  whatever.  Such  rootstocks  usually  are  stunted. 
This  tendency  might  be  overcome  by  planting  in  furrows.  Hilling- 
in  gradually  might  further  aid  by  raising  the  ground  to  a  level  with 
the  ascending  rootstock  growth.  An  experiment  was  begun  on  a 
number  of  0.1 -acre  plats  to  determine  the  effect  on  germination  and 
yield  of  planting  edible  canna  rootstocks  at  different  depths,  varying 
from  8  inches  below  the  surface  to  the  top  of  an  upraised  bed.  Mill- 
run  seed — that  is,  any  type  of  seed  with  a  visible  bud — was  planted 


Fig.  13.— Base  of  a  canna  hill  22  months  old.    Note  the  tendency  of  the  rootstocks  to  grow  above 

ground 

at  intervals  of  4  by  4  feet,  and  the  resulting  crop  wa,s  harvested  at 
20  months.     Table  9  gives  the  result  of  the  experiment. 


Table  9. — Effect  of  depth  of  planting  on  germination  and  yield  of  edible 

canna 

Plat 
No. 

Manner  of  planting 

Propor- 
tion of 
rootstocks 
failing  to 
germinate 

Gross 

yield  of 

rootstocks 

per  acre 

Net 

yield  of 

rootstocks 

per  acre 

Average 
weight 

per  root- 
stock 

20 

Hilled  in  gradually  in  12-inch  furrows 

Per  cent 
12.7 
8.8 
14.2 
11.1 
16.2 

Tons 
38.0 
37.9 
30.3 
37.5 
35.9 

Tons 
34.1 
34.0 
27.2 
33.6 
32.2 

Pound 
0.74 

21 

Planted  in  12-inch  furrows  (not  hilled  in) 

.67 

?,?, 

Planted  in  an  upraised  bed 

.59 

?3 

Level  culture;  seed  8  inches  deep 

.71 

?4 

Level  culture;  seed  1  inch  deep 

.68 

Little  difference  in  yield  or  average  weight  per  rootstock  was  ob- 
served in  the  plats,  except  in  the  upraised  bed  which  was  decidedly 
inferior  in  both  respects.     Plat  No.  20,  in  which  the  seed  was  planted 


EDIBLE     CANNA    IX    VVAIMEA    DISTRICT    OF    HAWAII 


23 


in  furrows  and  hilled  in  gradually,  produced  the  highest  yield  and 
the  largest  and  best  preserved  rootstocks.  The  strong  winds  of  the 
Waimea  district  frequently  blow  over  the  succulent  stalks  of  the 
canna  plant  and  in  so  doing  break  the  rootstoek.  Hilling-in  suffi- 
ciently covered  the  rootstoek-  to  save  them  from  damage1  by  the 
winds,  which  broke  the  stalks  instead  of  the  rootstocks.  The  same 
was  true  of  plat  No.  21  to  a  lesser  extent.  Plat  No  23  was  superior 
in  point  of  germination  and  yield  to  plat  No.  24.  In  the  latter  plat 
the  seed  was  planted  close  to  the  surface  of  the  soil  and  germinated 
more  slowly  and  with  greater  susceptibilitv  to  rot  than  was  the  case 
with  plat  No.  23. 

Furrow  planting  is  advantageous  in  preserving  canna  rootstocks, 
but  the  method  is  hardly  feasible  for  the  Waimea  district.  Not  only 
are  the  furrows  difficult  to  maintain  in  the  loose  soils  of  the  district, 
but  cross  cultivation  is  impossible.  This  proves  a  serious  disad- 
vantage where  hand  weeding  is  expensive.  It  seems,  therefore,  that 
level  culture,  placing  the  top  of  the  seed  at  least  4  inches  below  the 
soil  surface,  is  the  best  method  for  the  Waimea  district. 


NUMBER  OF  "SEED"  PER  HILL 


The  present  local  practice  is  to  plant  two  or  more  seed  pieces  in 
the  hill  in  the  hope  of  increasing  yield  and  eliminating  the  necessity 
of  replanting.  To  determine  the  effect  on  yield  of  planting  a  num- 
ber of  mill-run  seed  in  the  hill,  several  plats  were  planted  with  one 
to  four  seeds  per  hill.  The  seed  was  set  4  by  4  feet  apart,  and  the 
resulting  crop  was  dug  at  20  months.  Table  10  gives  the  results  of 
the  experiment. 

Table  10. — Effect  of  number  of  seed  per  hill  on  germination  and  yield  of  canna 


Plat  No. 

Area  of 
plats 

Number 
of  seed 
per  hill 

Propor- 
tion of 
seed 
failing  to 
germinate 

Gross 
yield  of 
root- 
stocks 
per  acre 

Net  yield 
of  root- 
stocks 
per  acre 

Average 
weight 
per  root- 
stock 

10 . 

Acre 
0.10 
.10 
.10 
.10 
.05 
.05 

1 

2 
3 
4 

Per  cent 

15.0 

2.7 

16.2 

1.9 

0 

0 

Tons 
35.2 
42.1 
38.8 
45.0 
38.4 
43.9 

Tons 
31.6 
37.7 
34.7 
40.3 
34.4 
39.3 

Pound 
0.55 

11 

.58 

18 

19 

9a  i 

.72 

9b  » 

.01 

Plats  Nos.  9a  and  9b  were  planted  seven  weeks  after  the  other  plats  in  the  area  of  plat  No.  9  in  which 
the  seed  failed  to  germinate  in  the  seed-selection  experiment. 

Planting  two  or  more  seed  to  the  hill  reduced  the  percentage  of 
nongermination  to  practically  nil.  The  two-seed  plantings  yielded 
at  the  rate  of  6.1  and  5.6  tons,  respectively,  greater  than  the  corres- 
ponding one-seed  plantings.  The  three  and  four-seed  plantings, 
which  are  seven  weeks  younger,  made  practically  the  same  yields  as 
the  one  and  two-seed  plantings,  respectively.  It  is  doubtful  whether 
the  three  and  four-seed  plantings  would  have  greatly  exceeded  the 
one  and  two-seed  plantings  had  they  been  allowed  to  grow  another 
seven  weeks. 

The  results  would  seem  to  show  the  superiority  of  the  two-seed 
planting  over  one-seed  planting.  From  the  standpoint  of  yield, 
however,  the  advantages  are  small,  since  the  additional  seed  weighs 


24  BULLETIN    57,    HAWAII    EXPERIMENT   STATION 

1  to  1 3^2  tons  per  acre,  the  cost  of  seed  selection  is  doubled  per  acre, 
and  the  cost  of  planting  is  increased.  For  these  reasons,  planting 
three  and  four  seed  to  the  hill  is  hardly  to  be  commended  where  the 
crop  is  grown  on  a  large  scale. 

SPACING  AND  MULCHING  WITH  CANNA  TOPS 

In  an  experiment  made  to  learn  the  effect  of  spacing  on  yields, 
edible  canna  plantings  were  made  on  0.1-acre  plats  at  distances  of 

2  by  4  feet,  3  by  4  feet,  4  by  4  feet,  and  3  by  3  feet.  Weeds  encroached 
upon  the  zone  of  the  resulting  crop  to  such  an  extent  as  to  render 
results  unreliable.  However,  the  present  practice  of  planting  at 
distances  of  4  by  4  feet  seems  to  be  desirable  for  Waimea  conditions. 
It  permits  cultivation  during  the  first  six  months'  growth  of  the  crop. 
After  this  time  weed  growth  is  held  in  check  by  the  luxuriant  foliage 
which  shades  the  ground.  Planting  at  distances  of  4  by  4  feet  also 
permits  cross  cultivation,  which  is  of  considerable  importance  in 
eliminating  hoeing. 

The  experiment  made  to  learn  the  efficacy  of  mulching  with  edible 
canna  tops  was  conducted  on  four  0.1-acre  plats.  The  rows  were 
top-dressed  immediately  after  planting  with  a  heavy  and  a  light 
mulch  of  fresh,  green  tops  and  with  partly  dried  tops.  Mulching 
was  expected  to  prevent  weed  growth  in  the  row  and  also  allow 
cultivation  between  the  rows.  All  plats  gave  depressed  yields. 
Mulching  caused  the  seed  to  rot,  depressed  the  rate  and  percentage 
of  germination,  and  had  little  effect  in  reducing  weed  growth  in  the 
row.  Part  of  the  mulch  remained  green  for  some  time,  and  this 
mulch  and  the  weed  growth  acted  as  hosts  for  cutworms,  which 
attacked  the  canna  stalks.  Mulching  with  canna  tops  apparently 
offers  no  advantage  for  the  crop  in  the  Waimea  district. 

FERTILIZERS 

Observations  on  the  growth  of  edible  canna  show  that  during  the 
first  three  months  after  planting  the  crop  grows  very  slowly  and 
produces  only  one  or  two  plants.  It  develops  much  more  rapidly 
during  the  next  three  months  and  at  the  end  of  six  months  bears 
many  vigorous  stalks  and  a  profusion  of  buds  which  are  ready  to 
develop.  For  these  reasons  fertilizer  was  thought  to  be  more  effi- 
cacious if  applied  to  the  crop  a  few  months  after  planting  rather  than 
at  the  time  of  planting.  It  was  thought  also  that  a  number  of  small 
applications  would  produce  better  results  than  one  large  application. 

At  the  central  station  in  Honolulu  a  fertilizer  containing  consider- 
able amounts  of  nitrogen  greatly  increased  top  growth  but  did  not  mate- 
rially increase  yield.  In  the  Waimea  district  mill-run  seed  was  planted 
at  distances  of  4  by  4  feet  on  0.1-acre  plats,  each  of  which  was  given 
a  total  of  100  pounds  of  fertilizer.  The  basal  formula  was  nitrogen 
(N)  5  per  cent  (as  ammonium  sulphate),  phosphoric  acid  (P205)  8  per 
cent  (as  superphosphate),  and  potash  (K20)  10  per  cent  (as  potas- 
sium sulphate).  The  field  was  harvested  at  20  months.  Table  11 
gives  the  result  of  the  experiment. 


EDIBLE    CANNA   IN   WAIMEA   DISTRICT   OP   HAWAII 


25 


Table  11. — Effect  of  time  and  number  of  applications  of  fertilizer  on  yield  of 

edible  canna 


Plat 

No. 


Number 
of  appli- 
cations 


1 
Control. 
1 
1 
Control. 
2 
3 


Time  of  application 


At  time  of  planting... 

Three  months  after  planting 

Six  months  after  planting 

Three  and  six  months  after  planting 

At  time  of  planting,  and  three  and  six  months  after  planting 


Gross 

Net  yield 

yield  of 

of  root- 

rootstocks 

stocks 

per  acre 

per  acre 

Tons 

Torts 

42.0 

37.7 

40.7 

36.  6 

41.9 

37.  5 

42.1 

37.7 

41.3 

37.  0 

43.2 

43.6 

3<J.  1 

Although  the  response  to  fertilizer  was  slight,  the  fertilized  plats 
made  higher  yields  than  the  unfertilized  (control)  plats  in  all  cases. 
Plat  No.  7  gave  the  greatest  increase  in  yield,  2.1  tons  per  acre. 
Weighings  of  individual  hills  showed  no  differences  in  average  size  of 
rootstocks  in  the  fertilized  and  unfertilized  plats.  The  value  of  the 
increment  of  2.1  tons  at  $3.50  per  ton  is  only  $7.35,  whereas  the 
fertilizer  applied  cost  $33.  These  data,  while  very  fragmentary, 
would  seem  to  indicate  that  on  the  rich  and  almost  virgin  soils  of 
the  best  lands  of  the  district,  immediate  fertilization  is  not  necessary. 
However,  analyses  given  in  another  part  of  this  bulletin  show  that 
a  crop  of  canna  rootstocks  removes  the  equivalent  of  1,200  pounds 
of  high-grade  fertilizer  from  the  soil.  This  heavy  drain  must  event- 
ually be  met  by  equivalent  returns  of  fertilizer.  On  the  poorer  lands 
of  the  district  it  is  probable  that  an  immediate  response  to  fertilizer 
can  be  had. 

TIME  OF  HARVESTING 

The  best  age  at  which  to  harvest  the  canna  crop  is  a  much-disputed 
question.  Since  in  Hawaii  canna  grows  continuously  though  irregu- 
larly, it  can  not  be  definitely  stated  when  the  crop  is  mature.  In 
Queensland,  where  growth  is  checked  by  cool  weather  and  frosts 
during  the  winter,  the  crop  is  harvested  at  10  months  of  age,  or  when 
the  rootstocks  "  indicate  their  maturity  by  the  triangular  slit  in  the 
outer  scale  leaf  of  the  bulb  assuming  a  purple  color."3  However,  it 
is  further  stated  that  the  crop  may  be  held  over  during  the  winter 
for  a  second  season's  growth.  These  observations  do  not  seem  to 
apply  to  Waimea  where  the  climate  is  rather  uniform. 

To  determine  the  monthly  increments  of  growth,  two  1-acre  plats 
were  planted  with  edible  canna,  one  receiving  seed  at  the  rate  of 
one  per  hill  and  the  other  at  the  rate  of  two  per  hill.  The  resulting 
crop  was  harvested  from  0.1 -acre  areas  in  each  plat  every  month, 
beginning  with  the  ninth  after  planting  and  continuing  through  the 
twentieth  month. 

The  following  notes  made  from  time  to  time  show  distinct  differences 
in  the  growth  of  the  crop : 

February  12,  1925:  Whole  field  growing  vigorously.  First  blooms  appearing 
and  stalks  8  to  10  feet  high.     Many  large  spikes  evident. 

April  16:  Last  two  months  have  been  cold  and  wet.  Vigorous  growth  of 
February  apparently  checked.  Many  spike  rootstocks  apparent  with  a  large 
proportion  of  spikes  dead,  as  is  indicated  by  discoloration  at  apex  of  rootstock. 


»  Personal  correspondence  from  H.  C  Quodling,  Director  of  Agriculture,  Department  of  Agriculture 
and  Stock,  Brisbane,  Queensland. 


26 


BULLETIN    57,    HAWAII   EXPERIMENT   STATION 


June  6 :  New  top  growth  observed,  also  new  leaves  at  apex  of  even  the  oldest 
stalks.  The  new  tops  are  mostly  of  young  Group  3a.  A  long  break  between  the 
new  and  old  stalks,  which  latter  belong  mostly  to  old  Group  2.  Some  new  root- 
stocks  growing.  New  top  growth  is  developing  from  old  rootstocks  growing  in 
February. 

August  8:  Hard  winds  of  past  two  months  blew  down  many  old  stalks.  Field 
looks  like  a  new  one.  The  new  tops  average  medium  to  old  Group  3a.  New 
rootstocks  apparent,  but  small. 

November  17:  A  profusion  of  new  spikes  developing  with  little  or  no  new  top 
growth. 

February,  1926:  Very  little  growth  of  either  stalks  or  rootstocks  since  Novem- 
ber. Hard  winds  (kona)  flattened  most  of  the  existing  top  growth.  Many 
spikes  beginning  to  develop,.     New  top  growth  expected. 

Table  12  gives  the  monthly  yields  and  tare  of  the  crop. 


Table  12. — Monthly  harvests  and  tare  of  one  and  two  seed  plantings  from  0.1-acre 

plats 


Age  of 

crop  in 

.months 


Month  of  harvesting 


1925: 

April 

May 

June 

July 

August 

September 
October. .. 
November 
December. 
1926: 

January... 
February . 


Tare 


Per  cent 
12.7 
12.7 
11.0 
15.5 
12.1 
11.4 
15.3 
8.9 
8.0 


9.8 


One-seed  planting 


Gross 

yield 

per  acre 


Tons 
15.09 
17.25 
18.75 
18.60 
23.20 
29.85 
32.90 
38.20 
40.75 

44.93 
47.60 


Net 

yield 

per  acre 


Tons 
13.17 
15.06 
16.69 

2  16.  37 
20.39 
26.45 

2  28.  95 
34.80 
37.51 

40.48 
42.93 


Monthly 
incre- 
ment 


Tons 


1.89 
1.63 


3  3.70 
6.06 
2.50 
5.85 
2.71 

2.97 
2.45 


Two-seed  planting 


Gross 

yield 

per  acre 


Tons 
21.70 
26.50 
28.58 
27.82 
30.25 
33.23 
37.00 
40.90 
44.25 

46.55 
48.70 


Net 

yield 

per  acre 


Tons 
18.94 
23.13 
25.44 

2  24.48 
26.59 
29.44 

3  32.  56 
37.26 
40.71 

41.94 
43.93 


Monthly 
incre- 
ment 


Tons 


4.19 
2.31 


3  1.15 
2.85 
3.12 
4.70 
3.45 

1.23 
1.99 


1  Tare  was  ascertained  monthly  by  determining  the  proportion  of  adhering  soil,  roots,  dead  scales,  and 
^excess  stems  on  about  200  pounds  of  rootstocks.     (See  also  "Tare,"  p.  34.)  • 

J  The  very  high  tare  values,  together  with  actual  decreases  in  yields  in  two  instances,  brought  into  question 
the  accuracy  of  the  tare  values.  Therefore  12  per  cent,  the  average  tare  of  the  other  months  up  to  Novem* 
ber,  was  used  to  compute  the  tare  weights. 

*  Increment  based  on  June  harvest  since  the  yields  in  July  were  less  than  in  June. 

Table  12  shows  a  nearly  continuous  though  irregular  growth  of 
canna  from  9  to  19  months,  inclusive.  The  rootstocks  increased 
both  in  number  and  in  weight.  From  April  to  July,  inclusive,  the 
rate  of  growth  constantly  decreased.  Beginning  with  August, 
growth  was  resumed,  reaching  its  maximum  in  November,  when  it 
again  decreased. 

For  the  first  12  months  of  growth  (until  August,  1925)  the  two-seed 
planting  was  decidedly  superior  to  the  one-seed  planting.  The 
July  harvest  of  the  former  yielded  24.48  tons  per  acre  net,  whereas 
that  of  the  latter  yielded  only  16.37  tons.  Beginning  with  the 
thirteenth  month  the  one-seed  planting  grew  more  rapidly  than  the 
two-seed  planting  and  at  19  months  it  lacked  only  a  ton  of  equaling 
the  latter.  These  results  are  somewhat  different  from  those  given  in 
Table  10,  where  the  two-seed  plantings  are  shown  to  have  exceeded 
the  one-seed  plantings  by  6.1  and  5.6  tons,  respectively.  The  large 
monthly  increments  of  the  one-seed  planting  in  the  last  seven  months 
of  growth  may  have  been  due  partly  to  differences  in  seed  or  fertility 
of  soil. 

Sixteen  hills  were  selected  at  regular  intervals  from  each  of  the 
plats  and  classified  according  to  the  method  outlined  under  "  Classifi- 
cation/ '  page  12.     Table  13  gives  the  results. 


EDIBLE    CANNA   IN    WAIMEA    DISTRICT   OF    HAWAII 


27 


Table  13. — Classification  of  monthly   harvests  from   one   and    tiro  seed   plantings 

from  0.1 -acre  plats 

NINTH   MONTH    (APRIL) 


One-seed  planting 

Two-seed  planting 

Group 

Number  of 
rootstocks 

Weight  of 
rootstocks 

Average 
weight  of 
rootstocks 

Number  of 
rootstocks 

Weight  of 
rootstocks 

Average 
weight  of 
rootstocks 

1.. 0 

Pounds 

Pounds 

Pounds 

Pounds 

2 

3i 

7.0 
12.8 

4.8 
5.9 

0.69 
.46 

10.9 
16.9 

7.1 

8;  4 

0.65 
.50 

HUP.. - 

19.8 

10.7 

.54 

27.8 

15.5 

.56 

TENTH   MONTH    (MAY) 


ELEVENTH   MONTH    (JUNE) 


TWELFTH   MONTH    (JULY) 


THIRTEENTH    MONTH    (AUGUST) 


FOURTEENTH   MONTH    (SEPTEMBER) 


1 





Hill 

0 

9.3 
13.1 

1_. 

3... 

6.5 
7.9 

0.70 
.60 

11.6 
16.9 

8.9 
9.  5 

0.77 
.56 

22.4 

14.4 

! 

.64 

28.5 

18.4  j 

.65 

1... 

0.3 
9.0 
11.5 

0.1 
6.0 
6.9 

0.33 
.67 
.60 

0.5 
12.8 
15.5 

0.1 
8.9 
9.8 

0.20 

2.. 

.70 

3 

.63 

Hill 

20.8 

13.0 

.63 

28.8  | 

18.8 

.65 

1.. 

0.4 

0.1 

0.25 

0.9 

0.4 

0.44 

2_. 

10.2 

7.3 

.72  1 

12.0 

8.3 

.69 

3... 

Hill. 

9.9 

5.7 

.58  | 

18.6 

9.9 

.53 

20.5 

13.1 

.64  • 

31.5 

18.6 

.59 

1... 

2... 
3... 

Hill 

2.5 
13.2 
13.0 

1.5 
10.0 
6.4 

0.60 

.76 
.49 

3.2 
13.8 

17.7 

1.4 
9.3 

8.8 

0.44 
.67 
.50 

28.7 

17.9 

.62 

34.7 

19.5 

.56 

1... 
2... 
3... 

Hill— . 

5.8 
11.5 
16.4 

4.0 
11.2 
9.9 

0.69 

.97 
.60 

1 
12.fi 

14.6 
19.5 

7.3 
12.1 
8.4 

0.58 
.83 
.43 

33.7 

25.1 

.74 

46.6 

27.8 

.60 

FIFTEENTH 

MONTH 

(OCTOBER) 

1 

10.8 
17.0 

4.2 

10.0 
10.2 

0.  65 
.93 
.00 

I6.fi 

16.0 
18.8 

9.9 
12.7 
8.3 

0.64 

2 

.79 

3 

.44 

Hill 

34.3 

24.4  I 

.71 

.50.3 

30.9 

.61 

28 


BULLETIN    57,   HAWAII   EXPERIMENT   STATION 


Table  13. — Classification  of  monthly  harvests  from  one  and  two  seed   plantings 
from  0.1 -acre  plats — Continued 

SIXTEENTH  MONTH  (NOVEMBER) 


One-seed  planting 

Two-seed  planting 

Group 

Number  of    Weight  of  \  A^ffi 
rootstocks    rootstocks    ^K^ 

1 

Number  of    Weight  of 
rootstocks  ,    rootstocks 

Average 
weight  of 
rootstocks 

1                      

9.3 
10.2 
17.3 

Pounds 
6.8 
10.0 
9.1 

Pounds 
0.73 
.98 
.53 

12.7 
14.4 
17.2 

Pounds 
8.8 
12.9 
8.6 

Pounds 
0.69 

2 

.90 

3 

.50 

Hill. 

36.8 

25.9 

.70 

44.3 

30.3 

.68 

SEVENTEENTH  MONTH  (DECEMBER) 

1 

■ 
14.2                10.0 
13.9                10.8 
20. 4                10. 0 

0.70 
.78 
.49 

20.3 
15.2 
20.1 

14.5 
11.3 
8.8 

0.71 

2 

.74 

3 

.44 

Hill 

48.5                30.8 

.63 

55.6 

34.6 

.62 

EIGHTEENTH  MONTH  (JANUARY) 


1 

2 

15.0 
9.8 
20.7 

11.1 
8.5 
10.4 

0.74 

.87 
.50 

22.5 

15.2 
25.2 

14.1 
10.8 
11.0 

0.63 
.71 

3 

.44 

Hill 

45.5 

30.0 

.66 

62.9 

35.9 

.57 

NINETEENTH  MONTH  (FEBRUARY) 


1 

19.5 
11.0 
21.3 

15.6 
7.9 
9.0 

0.80 

.72 
.42 

21.9 

16.6 
21.1 

16.0 
10.4 
7,7 

0.73 

2 

.63 

3 

.37 

Hill 

51.8 

32.5 

.63 

1 

59.6 

34.1 

.57 

i  Groups  3a  and  3&  are  placed  together  since  the  division  between  these  subgroups  had  to  be  changed  a 
number  of  times.    This  does  not  affect  the  total  for  Group  3. 
»  Each  "hill"  is  the  average  of  16  classified  hills. 

A  consideration  of  Table  13  show^s  that  the  first  rootstocks  of 
Group  1,  dormant  stage,  first  appear  in  the  eleventh  month  harvest. 
After  that  time  the  number  increases  rapidly.     (Figs.  14  and  15.) 

Group  1  shows  a  very  close  correlation  in  both  the  one  and  two- 
seed  plantings  with  the  hill  as  a  whole,  and  the  increases  in  the  monthly 
harvests  beginning  with  August. 

Group  2  shows  little  correlation  either  with  the  number  of  root- 
stocks  or  weight  of  the  hill  as  a  whole.  In  the  two-seed  planting  the 
number  gradually  increases  from  10.9  at  9  months  to  16.6  at  19 
months,  whereas,  in  the  one-seed  planting  it  increases  from  7  at  9 
months  to  13.2  in  the  thirteenth  month,  and  thence  decreases  with 
one  exception  to  a  fairly  constant  level  of  between  9.8  and  11. 

In  Group  3  the  number  remains  roughly  constant  in  the  two-seed 
planting  until  the  seventeenth  month,  ranging  from  15.5  to  19.5,  with 
a  sharp  increase  to  25  at  18  months.  In  the  one-seed  planting  the 
number  decreases  from  13.1  in  the  tenth  month  to  9.9  in  the  twelfth 
month  and  increases  steadily  to  21.3  in  the  nineteenth  month. 


EDIBLE   CANNA   IN   WAIMEA   DISTRICT   OF  HAWAII 


29 


In  average  weight  per  rootstock.  Group  1  of  the  two-seed  planting 
has  an  initial  value  of  0.2  pound  in  the  eleventh  month  and  a  final 
value  of  0.73  pound  at  the  nineteenth  month.  Group  1  of  the  one- 
seed  planting  has  an  initial  value  of  0.33  pound  in  the  eleventh 
month  and  a  final  value  of  0.8  pound  in  the  nineteenth  month. 

In  average  weight  per  rootstock,  Group  2  of  the  two-seed  planting 
was  fairly  constant,  ranging  from  0.65  to  0.83  pound,   until  the 


s> 


/O  //  /2  AS  Af  /S  AS  /7 

/V&r      <SCA/S       <SC/£r        >4L/&.       .52WT        OCT.  A/OV.        Z>fC. 


/<9  /£> 


Fig.  14.— Tenth-acre  harvests  and  classifications  of  "one-seed"  plat 

fourteenth  month;  it  increased  to  0.9  pound  in  the  sixteenth  month, 
and  subsequently  decreased  to  0.63  pound  in  the  nineteenth  month. 
A  similar  variation  occurs  in  the  one-seed  planting,  the  maximum  at 
the  sixteenth  month  being  0.98  pound  per  rootstock. 

The  close  correlation  in  results  between  the  one  and  two-seed 
plantings  together  with  the  classification  would  seem  to  verify  the 
essential  accuracy  of  the  results,  notwithstanding  changes  due  to 
variations  in  seed,  soil,  and  tare  values. 


30 


BULLETIN    57,   HAWAII   EXPERIMENT   STATION 


The  comparatively  small  increases  in  the  yields  during  June  and 
July,  the  sudden  increase  beginning  with  August,  and  the  appearance 
of  Group  1  in  appreciable  numbers  indicate  a  cyclic  rather  than  a 
continuous  growth  of  the  plant.  (Fig.  16.)  From  February  until 
May  few  new  rootstocks  appeared  and  practically  all  the  stalk  growth 
was  mature,  Group  3  consisting  largely  of  spikes.  New  stalk  growth 
appeared  in  June  and  many  new  rootstocks  in  August.  If  these 
phenomena  are  inherent  in  the  plant,  the  first  cycle  of  growth  ended 


S>  /0 


//  /£  /3  A?  /S  /&  /7  /&  /£> 

</v/vf   <J6/iy    ^ve.     S£/>t:     ocr      /vov     /?sc.     ^y^/v    /vb 


Fig.  15.— Tenth-acre  harvests  and  classifications  of  "two-seed"  plat 


about  June,  and  the  two  or  three  earlier  months  constituted  the 
maturing  period.  The  sudden  new  growth  of  stalks  in  June  and  new 
rootstocks  in  August  might  then  indicate  the  beginning  of  the  second 
cycle  of  growth. 

Climatic  factors  undoubtedly  have  their  effect  on  growth.  Except 
for  young  fields  planted  six  to  eight  months  or  less,  observations 
show  a  similarity  in  the  growth  of  fields  of  different  ages  in  the  same 
locality.  Among  the  climatic  factors,  destructive  winds  have  a 
bearing  on  the  crop.     During  December,  1925,  for  example,  a  severe 


EDIBLE    CANNA   IN   WAIMEA   DISTRICT   OP   HAWAII 


31 


wind  flattened  most  of  the  stalk  growth,  which  was  shortly  replaced 
by  numbers  of  new  stalks.     (Fig.  17.)     Growth  proceeds  irregularly 


Fig.  16. 


-Cyclic  growth  of  canna  plants,  14  months  old.    Note  the  first  cycle  of  old  mature  tops 
and  the  second  cycle  of  young  immature  stems 


regardless  of  whether  the  cyclic  tendency  is  inherent  or  climatic,  or  a 
combination  of  both.  A  field  at  one  stage  may  appear  rather  old 
with  most  of  its  stalks  having  only  the  apical  leaves  green;  the 


32 


BULLETIN    57,   HAWAII   EXPERIMENT  STATION 


same  field  three  months  later  may  appear  quite  young  due  to  its 
profusion  of  new  stalk  growth.  Two  months  later  still,  new  root- 
stocks  in  appreciable  numbers  may  be  found  growing.  This  would 
seem  to  be  the  order  of  growth  rather  than  a  steady,  simultaneous 
growth  of  rootstock  and  top.  The  cyclic  tendency  is  partly  masked 
in  the  results  of  monthly  harvests  since  growth  within  the  rootstock 
increases  the  yields  regardless  of  whether  new  rootstocks  develop. 
Previous  consideration  of  the  relation  of  classification  to  growth 
indicated  the  contemporaneous  appearance  of  Group  1  with  the  sud- 
den increases  in  the  new  growth  of  the  hill.  Moreover,  the  curve 
for  this  growth  follows  very  closely  the  curve  for  the  total  number 
of  rootstocks  in  the  hill.  Whether  this  is  the  cause  or  the  effect 
of  the  new  growth  is  not  known,  however.  Of  the  three  groups, 
Group  2  would  naturally  be  expected  to  be  the  most  constant  and 


Fig.  17.— Cyclic  growth  of  canna  plants,  24  months  old.  Note  the  vigorous  top  growth  which  has 
sprung  up  as  the  result  of  a  windstorm  which  blew  down  all  the  old  stems.  The  rootstocks  are 
nearly  all  undersized. 

to  show  a  tendency  toward  gradual  increase  as  the  size  of  the  hill 
increased.     This  is  well  exemplified  in  the  two-seed  planting. 

The  results  of  Group  3  show  little  correlation  between  the  irregu- 
lar and  the  cyclic  nature  of  the  new  growth  of  the  hill.  Unfortunately 
a  definite  division  was  not  established  between  the  subgroups  3a 
and  3b  4  during  the  progress  of  the  experiment.  Obviously,  a  group 
comprising  all  the  stages  of  growth  from  that  of  the  youngest  spike 
up  to  the  mature  stage  would  hardly  indicate  monthly  variations. 
Moreover,  after  a  long  dormant  period  a  spike  may  develop  a  stalk 
and  thus  remain  in  Group  3a  much  longer  than  would  be  the  case 
did  the  stalk  develop  normally.  Apparently  Groups  2  and  3  to- 
gether maintain  a  relatively  constant  but  slowly  increasing  number 
of  rootstocks  in  the  hill,  the  increase  in  the  total  number  in  the  hill 
being  largely  accounted  for  in  Group  1. 

*  Since  the  completion  of  this  investigation  the  classification  method  has  been  revised,  Group  3  being 
further  subdivided  into  Group  3c  which  includes  those  rootstocks  just  emerging  from  the  developing  bud 
stage.  In  addition  the  number  of  spikes  and  stalks  are  noted  in  each  group.  It  is  belived  that  these  re- 
visions will  furnish  data  concerning  the  top  growth  and  make  the  method  more  responsive  to  new  growth 

in  the  hill. 


EDIBLE   CANNA   IN   WAIMEA   DISTRICT   OF   HAWAII  33 

The  small  average  weight  of  rootstocks  in  Group  1  during  the 
months  of  June  and  July  is  due  to  the  fact  that  the  first  rootstocks 
which  become  dormant  are  of  the  small  cylindrical  type.  During 
the  subsequent  months  the  larger  surface  types  pass  over  into  Group 
1,  thus  giving  rise  to  rapid  increases  in  average  weight  until  at  the 
nineteenth  month  this  value  exceeds  that  of  the  other  groups. 

A  number  of  factors  are  to  be  considered  in  determining  the  proper 
age  at  which  to  harvest  the  canna  crop: 

(1)  The  total  yields  continue  to  increase  up  to  19  months,  and 
probably  until  the  rootstocks  of  Group  1  ultimately  rot,  at  which 
time  the  value  would  become  constant.  From  the  standpoint  of 
total  yield  harvesting  should  be  deferred  until  the  dormant  root- 
stocks  begin  to  deteriorate,  which  usually  takes  place  between  18  and 
24  months.  Cultivation  ceases  after  the  first  6  or  7  months  and  the 
only  expenditure  for  increase  in  yields  after  this  period  is  for  rental 
of  the  land  occupied  by  the  crop. 

(2)  The  manufacture  of  clean,  white  starch  becomes  increasingly 
difficult  after  the  plants  reach  a  certain  stage.  Even  though  the 
oldest  rootstocks  have  not  actually  begun  to  rot  they  become  watery 
and  discolor  quickly  when  opened,  and  the  cortex  becomes  dry  and 
corky.  The  surfaces  of  the  rootstocks  which  have  been  broken  by 
the  action  of  the  wind  partly  decay  and  exude  sap  which  mixes  with 
the  soil  and  forms  a  hard  mass.  Although  the  starch  granules  ap- 
parently are  not  affected  under  such  conditions,  the  discolored 
tissue  and  adhering  soil  interfere  materially  with  the  refining  of  the 
product. 

(3)  As  the  hill  grows  beyond  a  certain  stage,  much  of  the  younger 
growth  of  its  rootstocks  is  small.  This  fact  is  not  perceptible  from  a 
distance.  The  field  may  have  a  strong,  vigorous  top  growth  and 
stunted  rootstocks.  The  latter  may  add  considerably  to  the  weight 
of  the  hill,  but  they  are  not  desirable  for  starch  manufacture.  Not 
only  do  they  increase  the  difficulties  incident  to  washing  but  they 
are  low  in  actual  starch  content. 

(4)  In  a  previous  bulletin  (9)  the  starch  content  of  a  canna  roots tock 
was  shown  to  vary  from  2.08  to  27.92  per  cent,  Group  3  containing  the 
lowest.  Obviously  a  field  having  a  comparatively  large  part  of  its 
total  weight  in  this  group  would  yield  less  starch  per  ton  of  rootstocks 
than  it  would  if  this  growth  were  allowed  to  reach  the  Group  2 
stage.  In  practice  this  point  is  hard  to  determine  because  of  the 
prevalence  in  the  field  of  new  growth  at  all  times.  However,  the 
relative  proportion  of  Group  3  to  the  total  weight  of  the  hill  decreases 
from  approximately  50  per  cent  at  9  months  to  about  25  per  cent  at 
19  months.  It  is  concluded,  therefore,  that  the  longer  the  hill 
remains  in  the  ground  the  higher  will  be  the  proportionate  yield  of 
rootstocks  of  high  starch  content. 

Before  the  proper  age  at  which  to  harvest  the  crop  can  be  definitely 
determined  experiments  similar  to  the  one  undertaken  will  have  to 
be  repeated  many  times  to  take  into  account  different  seasons,  times 
of  planting,  and  soils.  The  available  data  seem  to  show  that  the 
crop  should  be  allowed  to  grow  until  the  new  growth  becomes  of 
undesirable  size,  or  until  the  dormant  Group  1  gives  signs  of  deteri- 
orating. In  the  foregoing  experiment  this  would  be  between  17 
and  18  months. 


34 


BULLETIN    57,    HAWAII   EXPERIMENT   STATION 


In  harvesting  edible  canna  considerable  dirt,  dead  scales,  and 
leaves  adhere  to  the  rootstocks  and  must  be  deducted  from  the  gross 
weight  in  determining  the  net  production  of  material  for  use  in  starch 


Fig.  18.— Juncture  of  stem  and  rootstock  of  canna.  o  Indicates  the 
apex  of  the  rootstock,  the  stem  being  characterized  by  parallel 
vascular  bundles 

manufacture.  Table  12  (p.  26)  shows  that  the  tare  varies  consider- 
ably from  month  to  month.  During  the  early  part  of  the  harvests 
the  percentages  ranged  from  11  to  15.5,  whereas  later  they  varied 
from  8  to  9.9.     The  variations  are  due  partly  to  the  fact  that  har- 


EDIBLE   CANNA   IN   WAIMEA   DISTRICT   OF   HAWAII  35 

vesting  on  a  large  scale  is  as  yet  an  unstandardized  procedure,  and 
partly  to  the  employment  of  untrained  help  in  the  work  of  harvest- 
ing, making  it  impossible  to  insure  that  the  tops  are  severed  with  the 
same  average  length  of  stem  attached  to  the  rootstocks.  In  addi- 
tion, the  quantity  of  roots,  dead  scales,  and  soil  adhering  to  the  canna 
rootstocks  varies  under  different  weather  conditions. 

Lack  of  precision  in  cutting  off  the  top  at  the  exact  apex  of  the 
rootstock  makes  it  difficult  also  to  estimate  the  tare.  In  the  sub- 
surface types  the  exact  juncture  of  rootstock  and  stalk  can  be  deter- 
mined only  by  a  careful  inspection  of  a  longitudinally  cut  section  of 
the  rootstock.  (Fig.  18.)  During  later  harvests  great  care  was  taken 
to  cleanse  the  rootstocks  of  all  adhering  soil  and  to  cut  the  tops  as 
closely  as  possible  to  the  rootstocks  so  that  the  tare  values  would  be 
more  nearly  constant.  The  values  can  not  be  assumed  to  be  constant, 
however,  since  they  are  so  easily  affected  by  the  factors  mentioned 
above. 

The  tare  will  likely  have  to  be  estimated  in  actual  operation, 
especially  if  the  rootstocks  are  purchased  by  the  ton  from  growers. 
Two  methods  of  procedure  are  feasible  for  the  purpose.  One  is 
that  used  in  the  present  study.  If  accurate  results  are  expected 
considerable  care  must  be  exercised  in  the  selection  of  representative 
samples  and  determination  must  be  made  on  lots  of  good  size.  In 
the  second  method,  the  price  per  ton  is  based  on  the  percentage  of 
starch  extracted.  A  basic  price  could  be  paid  plus  a  bonus  for  each 
percentage  of  extraction  over  the  minimum.  The  actual  percentage 
of  starch  in  the  rootstock  could  be  determined  by  attaching  a  con- 
tinuous sampler  to  the  shredder.  The  second  method  seems  prefer- 
able to  the  first  since  it  takes  into  account  the  tare  and  also  differ- 
ences in  actual  percentage  of  starch  in  the  rootstock.  However, 
this  method  can  not  well  be  used  until  milling  operations  are  com- 
pletely standardized.  The  first  method  can  be  used  during  the  initial 
stages  of  the  industry. 

FEED  AND  FERTILIZER  VALUE  OF  CANNA  TOPS  AND  PULP 

In  order  to  determine  the  fertilizer  elements  in  the  different  parts 
of  the  canna  plant  and  the  value  of  these  parts  as  feed  and  as  green 
manure,  5  hills  of  canna  were  dug  from  an  18-month-old  field  at 
Waimea.  The  tops  were  classified  and  the  separate  groups  weighed. 
Approximately  50  pounds  of  rootstocks  were  shredded  and  the  starch 
extracted  by  repeatedly  washing  the  pulp  in  a  cloth  bag.  Samples 
of  the  pulp,  the  rootstocks,  and  the  three  groups  of  tops  were  then 
dried  and  analyzed  for  their  nutritive  and  fertilizer  constituents. 
Group  1  contained  an  even  distribution  of  shriveled  tops  and  tops 
the  stems  of  which  were  still  succulent.  Group  2  also  contained  an 
even  distribution  of  the  older  and  younger  members.  Group  3a 
was  largely  medium  to  old  and  contained  practically  none  of  the 
youngest  stalks  of  the  group.  Table  14  compares  the  composition 
of  different  parts  of  the  canna  plant  and  other  carbohydrate  feeds. 


36 


BULLETIN    57,   HAWAII   EXPERIMENT   STATION 


Table  14. 


■Composition  of  different  parts  of  the  canna  plant  and  other  carbohydrate 
feeds 


Material  and  source 

Water 

Fat 

Crude 
pro- 
tein 

Fiber 

Nitro- 
gen- 
free 

extract 

Ash 

Nitro- 
gen 

Lime 

Phos- 
phoric 
acid 

Potash 

Nutri- 
tive 
ratio 
lto  — 

Edible     canna     (air- 
dried  material) : 

Tops,  Group  1 

Tops,  Group  2 

Tops,  Group  3a 

Rootstock 

Per  cl. 
10.14 
10.18 
11.24 
4.36 
7.03 

77.00 
89.00 
89.70 
77.28 
77.28 

74.47 
79.30 
13.20 
12.00 

12.00 
8.40 

Per  ct. 
0.46 
.55 
.79 
.34 
.31 

.12 
.07 
.09 
.08 
.08 

.42 

.50 

2.50 

1.06 

.70 
.70 

Per  ct. 
3.35 
5.36 
7.46 
2.83 
1.99 

.86 
.66 
.86 
.67 
.49 

1.54 
1.80 
5.90 
7.42 

.80 
8.10 

Per  ct. 
31.93 
21.67 
21.43 
2.45 
9.78 

8.17 
2.64 
2.49 
.58 
2.39 

7.31 

5.00 

29.00 

10.61 

6.10 
17.50 

Per  ct. 
47.95 
54.05 
48.48 
85.29 
78.46 

12.27 

6.62 

5.63 

20.27 

19.17 

14.71 
12.20 
45.00 
65.72 

78.80 
60.80 

Per  ct. 
6.17 
8.29 

10.60 
4.73 
2.43 

1.58 
1.01 
1.23 
1.12 
.59 

1.55 
1.20 
4.40 
3.19 

1.60 
4.50 

Per  ct. 
0.54 

.86 
1.19 

.45 

.32 

.138 
.105 
.138 
.107 
.078 

.246 
.290 
.940 
1.080 

.120 
1.290 

Per  cl. 

1.29 
.93 
.78 
.10 
.27 

.330 
.113 
.090 
.024 
.067 

Per  ct. 
0.51 

.78 

.76 

.62 

.63 

.131 
.095 
.088 
.147 
.154 

Per  ct. 
1.15 
2.48 
3.52 
1.32 
.79 

.294 
.302 
.408 
.313 
.192 

Per  ct. 

14.6 

10.3 

6.8 

30  5 

Pulp 

Edible    canna    (fresh 
material): 

Tops,  Group  1 

Tops,  Group  2 

Tops,  Group  3a 

Rootstock. 

Pulp* 

39.5 

Other  comparable 
feeds: 
Sugar-cane  tops  *.. 

10.2 

Corn  fodder » 

Timothy  hay  * 

Potato  pomace «... 
Cassava  starch  re- 
fuse • 

::::::: 

.110 
.330 
.240 

.060 
.220 

.390 
1.420 
1.080 

.280 
.310 

7.4 
8.6 
9.2 

100.5 

Dried  beet  pulp  »__ 

7.7 

1  Calculated  to  same  moisture  basis  as  rootstocks. 

1  (i,  P.  5). 

*  (3,  app.,  Tables  I,  III.)    Potato  pomace  and  cassava  starch  refuse  were  calculated  to  air-dry  basis. 

A  comparison  of  the  composition  of  the  air-dried  material  of  the 
three  groups  of  canna  tops  and  the  rootstock  shows  a  gradual  decrease 
in  fat,  protein,  and  ash  in  progressing  from  Group  3a  to  Group  1  and 
thence  to  the  rootstock.  In  carbohydrates  the  tops  and  rootstocks 
vary  greatly,  due  of  course  to  the  storage  of  starch  in  the  latter. 
Lime  increases  with  the  increase  in  maturity  of  the  stem  but  drops 
to  a  very  low  value  in  the  rootstock.  Phosphoric  acid  and  potash 
decrease  in  the  older  tops  but  there  is  a  slight  increase  in  these 
elements  in  the  rootstock  over  the  proportion  in  the  oldest  tops. 

In  estimating  the  value  of  edible  canna  tops  as  green  feed,  Group  1 
should  not  be  considered  because  it  consists  of  dried  leaves  and 
partly  shriveled  stems  which  are  fibrous  and  unpalatable.  The 
greater  moisture  content  of  the  other  two  groups  over  that  of  sugar- 
cane tops  and  corn  fodder  decreases  their  fresh  green  value.  Reduced 
to  the  same  moisture  content,  the  three  feeds  have  similar  value. 

In  fertilizer  value,  the  average  of  the  three  groups  is  similar  to  the 
fertilizer  value  of  corn  fodder  in  both  phosphoric  acid  and  potash. 

Canna  pulp  as  a  feed  is  only  slightly  poorer  than  the  original  root- 
stock.  There  is  somewhat  less  nitrogen-free  extract  and  protein  in 
the  pulp  than  in  the  original  rootstock,  and  the  ash  content  decreases 
to  half  the  quantity  in  the  rootstock  due  largely  to  losses  in  potash. 
In  comparison  with  the  other  by-products,  canna  pulp  is  decidedly 
poorer  in  protein  and  richer  in  carbohydrates,  with  a  correspondingly 
wider  nutritive  ratio,  than  potato  pomace  and  dried  beet  pulp.  As 
compared  with  cassava  starch  refuse,  canna  pulp  is  richer  in  protein, 
but  has  a  much  narrower  nutritive  ratio. 

During  the  process  of  manufacture  water  is  used  copiously  to 
remove  the  starch  from  the  shredded  rootstock.  This  washing  is 
done  on  screens  of  60  to  80  meshes  to  the  inch,  so  that  in  addition  to 
the  starch,  certain  quantities  of  cellular  tissue,  colloidal  material, 
and  water-soluble  constituents  pass  through  the  screen  and  are  sub- 
sequently separated  from  the  pure  starch  by  fluming  and  levigation. 


EDIBLE    CANNA   IN   WAIMEA   DISTRICT  OF   HAWAII 


37 


In  order  to  approximate  the  quantity  of  the  various  constituents 
of  the  rootstock  lost  during  manufacture  and  the  proportion  retained 
by  the  pulp,  the  analysis  of  the  pulp  (Table  14)  was  recalculated  to 
percentages  of  the  original  rootstocks.  In  this  recalculation  the 
values  for  the  pulp  were  multiplied  by  the  factor  0.58/2.388,  the 
numerator  being  the  fiber  content  of  the  rootstock  and  the  denomi- 
nator representing  that  of  the  pulp,  it  being  assumed  that  the  fiber 
was  not  affected  by  the  washing  process.  Table  15  shows  what  con- 
stituents are  retained  by  the  canna  pulp  during  the  process  of  manu- 
facture. 

Table  15. — Constituents  of  canna  rootstocks  retained  by  the  pulp  during  the  process 

of  manufacture 


Constituent 

Rootstock 

Pulp 

Proportion 
in  pulp  of 

original 
rootstock  i 

Proportion 
in  pulp  of 
constitu- 
ents of  root- 
stocks  » 

Moisture 

Per  cent 

77.284 

.081 

.671 

.682 

20.260 

1.122 

.024 

.147 

.313 

Per  cent 

77.284 

.076 

.486 

2.388 

19. 173 

.593 

.067 

.154 

.192 

Per  cent 

Per  cent 

Fat 

Protein. 

Fiber 

Nitrogen-free  extract 

0.019 
.119 
.582 

4.672 
.145 
.016 
.037 
.047 

23.5 

18.0 

100.0 

23.1 

Total  ash 

12.9 

Lime  (CaO). 

66.7 

Phosphoric  acid  (PjOs) 

25.2 

Potash  (KjO) 

15.0 

»  Column  3  times  factor  0.58/2.388. 


1  Column  4  divided  by  column  2. 


Table  15  shows  that  the  proportions  of  the  various  constituents 
retained  by  the  pulp  are,  with  the  exception  of  that  of  lime,  very 
small.5  Potash  is  leached  out  to  the  greatest  extent,  followed  by 
protein,  carbohydrates,  fat,  and  phosphoric  acid,  in  the  order  named. 
Lime  is  outstanding  in  that  it  is  retained  in  the  pulp  to  more  than 
twice  the  extent  of  any  of  the  other  constituents.  The  predominance 
of  lime  in  the  stems  (Table  14)  suggests  that  it  is  contained  largely 
in  the  more  fibrous  tissue  of  the  rootstock  and  hence  is  less  subject 
to  leaching  than  are  the  other  constituents. 

Table  16  shows  the  pounds  per  acre  of  fertilizer  elements  contained 
in  one  crop  of  edible  canna.  The  composition  and  weights  of  the 
tops  and  rootstocks  are  based  on  the  harvest  of  the  five  hills  used  in 
the  analysis  given  in  Table  14.  The  " proportion  in  pulp  of  original 
rootstocks"  (Table  15,  column  4)  is  used  in  estimating  the  values  for 
the  pulp. 

Table  16. — Fertilizer  elements  in  one  crop  of  edible  canna  from  1  acre 


Part  of  plant 

Weight 
per  hill 

Weight 
per  acre 

Nitrogen 

Lime 

Phos- 
phoric 
acid 

Potash 

Tops: 

Group  1 

Pounds 

5.2 

26.8 

4.6 

Tons 
7.1 
36.4 
6.3 

Pounds 
19.6 

76.5 
17.4 

Pounds 
46.9 
82.3 
11.3 

Pounds 
18.6 
69.2 
11.1 

Pounds 
41.7 

Group  2 

219.9 

Group  3a„ 

51.4 

Total 

36.6 
22.4 

49.8 
30.0 

113.5 
64.2 

140.5 
14.4 

98.9 
88.2 

313.0 

Rootstocks 

187.8 

Whole  plant 

59.0 

79.8 

177.7 
11.5 

154.9 
9.6 

187.1 
22.2 

500.8 

Pulp 

28.2 

»  Based  on  the  assumption  that  the  fiber  was  lOOjper  cent  retained. 


38  BULLETIN    57,   HAWAII   EXPERIMENT   STATION 

Table  16  shows  that  the  top  growth  of  canna  requires  considerably 
more  fertilizer  elements  than  do  the  rootstocks.  The  former  require 
10  times  as  much  lime  as  the  latter,  about  double  the  quantities  of 
nitrogen  and  potash,  and  nearly  equal  quantities  of  phosphoric  acid. 
Stated  in  terms  of  commercial  forms  of  fertilizer,  the  tops  require  680 
pounds  of  nitrate  of  soda,  250  pounds  of  limestone,  495  pounds  of 
superphosphate  (acid  phosphate),  and  616  pounds  of  sulphate  of 
potash,  representing  a  total  of  2,041  pounds  of  fertilizer  returned  to 
the  soil  when  the  tops  are  plowed  under.  The  rootstocks  remove 
from  the  soil  approximately  385  pounds  of  nitrate  of  soda,  26  pounds 
of  limestone,  441  pounds  of  acid  phosphate,  and  376  pounds  of 
sulphate  of  potash,  or  a  total  of  1,228  pounds.  The  pulp  contains 
69  pounds  of  nitrate  of  soda,  17  pounds  of  limestone,  111  pounds  of 
acid  phosphate,  and  56  pounds  of  sulphate  of  potash,  totaling  253 
pounds.  If  the  pulp  and  tops  are  returned  to  the  soil  the  crop  will 
remove  the  equivalent  of  975  pounds  of  fertilizer. 

The  immature  tops  of  edible  canna  are  very  palatable  and  make  a 
nutritious  green  feed.  Nearly  all  the  leaves  of  the  mature  (dormant) 
tops  have  shriveled,  and  the  fibrous  stems,  although  not  very  palat- 
able, if  finely  cut  might  be  used  as  feed  because  of  their  sugar  content. 
If  the  whole  top  growth  of  the  hill  could  be  cut  so  as  to  avoid  hand 
selection  and  fed  fresh  or  as  silage,  quantities  of  the  tops  might  be 
used  on  the  near-by  ranches  for  green  roughage.  The  top  growth  is 
worth  more  than  a  dollar  per  ton  when  left  on  the  land  for  its  fer- 
tilizer elements. 

Field  methods  of  successfully  handling  the  tops  as  green  manure 
have  not  yet  been  developed.  If  the  field  is  cross  disked  immediately 
after  harvesting  with  a  heavily  weighted  disk,  the  tops  can  probably 
be  cut  into  short  lengths  and  plowed  under.  They  will  soon  rot  if 
kept  moist.  Decomposition  may  also  be  effected  by  placing  the 
tops  in  piles  or  windrows  across  the  field.  The  repeated  incorpora- 
tion in  the  soil  of  such  heavy  applications  of  succulent  green  matter 
may  eventually  have  a  deleterious  effect.  Allowing  a  partial  drying 
out  of  the  tissue  after  disking  and  before  plowing  under  would  be 
advantageous  from  this  standpoint. 

The  apparent  palatability  of  the  waste  pulp  from  the  starch  fac- 
tories suggests  its  use  as  a  carbohydrate  feed.  It  is  comparatively 
low  in  protein,  but  high  in  carbohydrates,  and  not  excessively  high 
in  fiber  content.  Locally  used  pulp  can  be  taken  from  the  factory 
direct  to  the  animals.  The  pulp  is  dried  in  the  same  manner  as 
starch  for  shipping.  The  dried  pulp  is  a  mixture  of  long,  coarse 
fibers  and  fine  tissue.  Grinding  and  sifting  facilitate  separation  of 
the  long  fibers  from  the  pulp  proper,  which  then  has  the  consistency 
of  bran.  To  the  pulp  can  be  added  the  brown  sludge  which  is  sepa- 
rated from  the  starch  during  purification. 

MANUFACTURE  OF  STARCH 

After  the  tops  have  been  cut,  the  rootstocks  are  dug  by  means  of 
a  tractor-drawn  middle  burster  having  a  high  beam.  They  are 
then  carried  to  the  mill  for  starch-making.  (Fig.  19.)  The  washing 
machine  consists  of  a  horizontal,  cylindrical  iron  drum  3J^  by  12  feet 
with  iron  slats  for  sides.  The  slats  are  2  inches  wide  and  are  separated 
by  intervals  of  an  inch.  The  drum  has  attached  to  its  perimeter  a 
worm  running  the  entire  length.     Wooden  cleats  running  parallel  to 


EDIBLE   CANNA   IN   WAIMEA   DISTRICT   OF   HAWAII 


39 


the  long  axis  of  the  drum  are  attached  at  intervals  between  succes- 
sive threads  of  the  worm.  The  rootstocks  are  fed  into  the  drum 
which  rotates  partly  under  water;  thence  they  are  worked  by  means 
of  the  worm  to  the  opposite  end  of  the  cylinder.  The  wooden  cleats, 
which  alternately  lift  and  drop  the  rootstocks,  facilitate  the  washing. 
The  rootstocks  are  next  run  into  the  hopper  of  the  grater.  This 
consists  of  a  sheet  of  perforated  iron  which  has  been  fitted  on  a  wooden 
cylindrical  core  36  inches  long  and  24  inches  in  diameter  to  form  the 
grater.  It  revolves  about  300  times  a  minute.  Water  is  copiously 
used  in  the  grating  process  to  facilitate  shredding  and  to  keep  the 
grater  clean.  The  pulp  from  the  rasper  is  then  led  into  a  revolving 
cylinder  the  surface  of  which  is  covered  with  brass  screening  (60 
meshes  to  the  inch).  The  cylinder  is  9  feet  long  and  3  feet  in  diam- 
eter. Fully  90  per  cent  of  the  extraction  is  done  by  this  machine. 
The  pulp  is  sprayed  with  water  and  passed  from  the  revolving  screen 


Fig.  19.— Interior  of  a  starch  mill  at  Waimea,  Hawaii 

to  the  first  beater.  This  is  a  sheet-iron  cylinder  2  feet  in  diameter  and 
8  feet  long  having  paddles  which  revolve  at  the  rate  of  240  times  a 
minute  attached  to  the  shaft.  The  beater  breaks  the  clumps  of 
pulp  and  releases  more  starch.  The  pulp  then  is  carried  from  the 
first  beater  to  the  first  shaking  screen  (80  meshes  to  the  inch).  This 
screen  is  4  feet  wide,  10  feet  long,  and  has  a  pitch  of  6  inches.  It  is 
driven  by  means  of  an  eccentric  which  works  the  pulp  gradually 
down  the  surface.  Water  is  again  sprayed  over  the  pulp  as  it  passes 
down  the  screen  to  facilitate  further  the  extracting  of  the  starch  and 
the  pulp  is  then  passed  into  a  second  set  of  beaters  and  screens. 

The  starch  water  from  the  three  screens  is  then  combined  and 
passed  through  a  set  of  three  shaking  screens  2  by  6  feet  each  (80, 
100,  and  120  meshes,  respectively,  to  the  inch)  for  the  removal  of 
fine  particles  of  pulp.  The  starch  water  is  then  run  into  the  flumes. 
These  are  140  feet  long,  18  inches  deep,  and  18  inches  wide,  and  are 
set  at  a  pitch  of  6  inches  to  140  feet.     The  starch  settles  in  the 


40  BULLETIN    57,   HAWAII   EXPERIMENT   STATION 

upper  part  of  the  flume,  permitting  the  lighter  particles  of  brown  tissue 
to  be  carried  off.  In  the  refining  process  the  starch  is  flushed  out 
of  the  flumes  into  settling  tanks  4  by  6  feet  and  3  feet  deep.  By 
repeated  levigation  and  removal  of  the  brown  sludge,  a  comparatively 
pure  form  of  starch  is  secured.  After  the  final  settling  the  starch  is 
agitated  with  water  and  pumped  into  a  30-inch  sugar  centrifuge. 
This  machine  reduces  the  moisture  content  of  the  starch  to  about 
40  per  cent  and  lessens  the  time  involved  in  drying  the  starch  by 
heat.  The  starch  is  then  broken  into  fine  pieces  and  placed  on  trays. 
These  in  turn  are  placed  for  24  hours  in  a  tunnel  drier  80  feet  long, 
6  feet  wide,  and  7  feet  high  and  resembling  the  ordinary  counter- 
current  fruit  dehydrator.  The  dried  starch  finally  is  powdered  and 
put  into  packages  for  marketing. 

The  starch  may  be  shipped  from  the  factory  either  by  way  of 
the  seaport  of  Kawaihae,  12  miles  distant  from  Kamuela,  which  is 
located  at  the  western  edge  of  the  agricultural  area,  or  by  railroad, 
which  terminates  at  Paauilo,  18  miles  to  the  eastward. 

SUMMARY 

The  possibilities  of  the  Waimea  district  as  a  canna-producing  region 
has  led  to  experiments  with  the  crop  on  a  field  scale  in  that  region. 

The  Waimea  district  is  a  slightly  rolling  table-land  (2,700  feet 
elevation)  between  Mauna  Kea  and  the  Kohala  Mountains.  The 
district  is  characterized  by  strong  winds  and  frequent  mists  and  fogs. 
The  soil  is  of  a  porous  nature  and  is  derived  largely  from  volcanic  ash. 
Most  of  the  soil  of  the  Homestead  tract  is  very  fertile. 

The  Waimea  district  is  devoted  to  small  diversified  farming,  but 
has  need  of  a  staple  field  crop  which  can  be  grown  throughout  the 
year  and  readily  converted  into  cash.  Edible  canna  gives  promise  of 
filling  this  need  provided  the  crop  can  be  utilized  as  a  commercial 
source  of  starch.  The  crop  is  especially  well  adapted  to. the  region 
notwithstanding  the  comparatively  low  annual  rainfall  (43.5  inches). 

Methods  of  study  of  the  edible  canna  are  outlined  which  make 
possible  the  progressive  study  of  the  growth  of  the  plant. 

Results  of  field  experiments  indicate  the  desirability  of  "seed" 
selection.  Of  the  various  types  of  rootstocks,  the  immature  root- 
stocks  with  one  or  two  buds  gave  the  highest  yields,  followed  by  sub- 
surface and  attached  spike  types.  Mature  rootstocks  with  no  visible 
bud,  detached  spikes,  and  secondary  immature  rootstocks  should  be 
thrown  out  in  selecting  planting  stock. 

Chemical  treatment  of  seed  did  not  prevent  rotting.  Rotting  of 
the  seed  does  not  affect  the  growth  of  the  hill  unless  development 
of  the  bud  is  delayed.  Under  Waimea  conditions,  seed  should  be 
planted  at  least  4  inches  deep  and  at  distances  of  4  by  4  feet  to  permit 
cross  cultivation.  Planting  two  seed  pieces  per  hill  insures  better 
germination  and  increases  the  yields  somewhat  but  also  increases  the 
costs  of  seed  selection  and  planting.  Mulching  with  canna  tops 
retarded  germination  and  was  not  successful  in  preventing  weed 
growth.  Fertilizers  failed  to  increase  the  yields  of  rootstocks  appre- 
ciably. This  is  attributed  to  the  high  fertility  of  the  soils  on  the 
experimental  field. 

Results  of  monthly  harvests  (ninth  to  nineteenth  month,  inclusive) 
from  one  and  two-seed  plantings  on  0.1 -acre  plats  showed  an  irregular 
but  nearly  continuous  growth  and  unusually  high  yields  of  rootstocks. 


EDIBLE   CANNA   IN   WAIMEA   DISTRICT   OF  HAWAII  41 

At  the  end  of  the  nineteenth  month  the  two-seed  planting  yielded 
43.93  tons  per  acre  and  the  one-seed  planting,  42.93  tons.  The  crop 
should  be  allowed  to  grow  until  the  new  growth  produces  rootstocks 
of  undesirable  size  for  starch  making,  or  until  the  older  rootstocks 
show  signs  of  deteriorating.  For  starch  manufacture  the  crop  should 
be  harvested  at  17  to  18  months. 

Progressive  studies  of  the  growth  of  the  plant  showed  it  to  be  of  a 
cyclic  nature  rather  than  uniform.  Periods  of  comparative  dormancy 
were  followed  by  periods  of  rapid  growth.  Probably  this  is  partly 
inherent  in  the  plant  and  partly  due  to  climate. 

Analyses  of  the  different  parts  of  the  canna  plant  show  that  the 
tops  are  of  value  both  as  feed  and  as  fertilizer.  The  stalks  from  an 
acre  of  land  contain  the  equivalent  of  over  a  ton  of  high-grade 
fertilizers.  An  acre  of  rootstocks  removes  from  the  soil  the  equiva- 
lent of  1,200  pounds  of  fertilizer.  During  the  process  of  manufacture 
the  pulp  loses  about  four-fifths  of  the  total  fertilizer  elements  con- 
tained in  the  rootstocks.  The  pulp  is  thought  to  have  excellent 
possibilities  as  a  carbohydrate  feed. 

The  process  of  manufacture  of  edible-canna  starch  is  described. 

LITERATURE  CITED 

(1)  Chung,  H.  L.,  and  Ripperton,  J.  C. 

1924.  edible    canna   in   Hawaii.     Hawaii  Agr.  Expt.  Sta.  Bui.  54,  16 

p.,  illus. 

(2)  Henry,  A.  J. 

1925.  Hawaiian    rainfall.     U.  S.  Mo.  Weather  Rev.  53:  10-14,  illus. 

(3)  Henry,  W.  A. 

1911.  feeds  and  feeding.     Ed.  11,  rev.  and  rewritten,  613  p.     Madi- 
son, Wis. 

(4)  Johnson,  M.  O.,  and  Ching,  K.  A. 

1918.    COMPOSITION     AND     DIGESTIBILITY     OF     FEEDING     STUFFS     GROWN 

in  Hawaii.     Hawaii  Agr.  Expt.  Sta.  Press  Bui.  53,  26  p. 

(5)  Kelley,   W.   P.,  McGeorge,   W.  [T.],  and  Thompson,  A.  R. 

1915.  the    soils    of    the    Hawaiian    islands.     Hawaii  Agr.  Expt. 
Sta.  Bui.  40,  35  p. 

(6)  McGeorge,  W.  T. 

1915.    EFFECT      OF      FERTILIZERS      ON      THE      PHYSICAL      PROPERTIES      OF 

Hawaiian  soils.     Hawaii  Agr.  Expt.  Sta.  Bui.  38,  31  p.,  illus. 

(7)  

1917.  composition     of     Hawaiian     soil     particles.     Hawaii  Agr. 
Expt.  Sta.  Bui.  42,  12  p. 

(8)  Ripperton,  J.  C. 

1924.    THE      HAWAIIAN      TREE      FERN      AS      A      COMMERCIAL      SOURCE      OF 

starch.     Hawaii  Agr.  Expt.  Sta.  Bui.  53,  16  p.,  illus. 

(9)  

1927.    CARBOHYDRATE    METABOLISM    AND    ITS    RELATION    TO    GROWTH    IN 

the  edible   canna.     Hawaii  Agr.  Expt.  Sta.  Bui.  56,  35  p., 
illus. 

(10)  Starratt,  H.  E. 

1924.    REPORT    OF    THE    COMMITTEE    ON    CULTIVATION    AND    WEED    CON- 
TROL.    Hawaii.  Planters'  Rec.  28:  48-55. 

(11)  United    States    Department    of    Agriculture,    Weather    Bureau. 

191&-26.  climatological       data.       Hawaii       section,     v.      15-22. 
Honolulu. 

(12)  

1926.  SUMMARY      OF     THE      CLIMATOLOGICAL      DATA      FOR     THE      UNITED 

STATES,         BY         SECTIONS.       HAWAII        SECT.       U.  S.   Dept.  Agr., 

Weather  Bur.  Bui.  W,  ed.  2,  v.  3,  illus. 


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